subsurface/Documentation/user-manual.txt

// Subsurface 4.5 User Manual
// ==========================
// :author: Manual authors: Jacco van Koll, Dirk Hohndel, Reinout Hoornweg,
// Linus Torvalds, Miika Turkia, Amit Chaudhuri, Jan Schubert, Willem
// Ferguson, Salvador Cuñat, Pedro Neves
// :revnumber: 4.5
// :revdate: October 2015
:icons:
:toc:
:toc-placement: manual
:numbered:
// :website: http://subsurface-divelog.org

image::images/Subsurface4Banner.jpg["Banner",align="center"]

[big]#USER MANUAL#

*Manual authors*: Willem Ferguson, Jacco van Koll, Dirk Hohndel, Reinout Hoornweg,
Linus Torvalds, Miika Turkia, Amit Chaudhuri, Jan Schubert, Salvador Cuñat, Pedro Neves

[blue]#_Version 4.5, October 2015_#


Welcome as a user of _Subsurface_, an advanced dive logging program with
extensive infrastructure to describe, organise, interpret and print scuba
and free dives. _Subsurface_ offers many advantages over other similar
software solutions:

 - Do you need a flexible way of logging dives using recreational equipment,
   even not using a dive computer?
 - Do you use two different dive computer brands, each with its own proprietary
   software for downloading dive logs? Do you dive with rebreathers as well
   as open circuit or recreational equipment? Do you use a Reefnet Sensus time-depth
   recorder in conjunction with a dive computer? _Subsurface_ offers a standard
   interface for downloading dive logs from all these different pieces of
   equipment and to store and analyse the dive logs within a unified system.
 - Do you use more than one operating system? _Subsurface_ is fully compatible
   with Mac, Linux and Windows, allowing you to access your dive log on each
   of your operating systems using a single application.
 - Do you use Linux or Mac and your dive computer has only Windows-based software
   for downloading dive information (e.g. Mares)? _Subsurface_ provides a way of
   downloading and analysing your dive logs on other operating systems.
 - Do you need an intuitive graphical dive planner that integrates with and takes
   into account the dives that have already been logged?
 - Do you need a way of storing or backing up your dive log on the Internet, allowing
   you to view your dive log from anywhere, using an Internet browser?

_Subsurface_ binaries are available for Windows PCs (Win XP or later), Intel
based Macs (OS/X) and many Linux distributions. _Subsurface_ can be built for
many more hardware platforms and software environments where Qt and
libdivecomputer are available.

The scope of this document is the use of the _Subsurface_ program. To install
the software, consult the _Downloads_ page on the
http://subsurface-divelog.org/[_Subsurface_ web site].
Please discuss issues with this program by sending an email to
mailto:subsurface@subsurface-divelog.org[our mailing list] and report bugs at
http://trac.hohndel.org[our bugtracker].  For instructions on how to build the
software and (if needed) its dependencies please consult the INSTALL file
included with the source code.

*Audience*: Recreational Scuba Divers, Free Divers, Tec Divers, Professional
Divers

toc::[]

[[S_UserSurvey]]
Using this manual
-----------------
When opened from within _Subsurface_, this manual does not have external controls. However,
a _SEARCH_ function is important. This is activated by pressing control-F or command-F on
the keyboard. A text box appears at the bottom of the window. Use this to search for
any term in the manual.

The user survey
---------------
In order to develop _Subsurface_ in a way that serves its users in the best possible way,
it is important to have some user information. Upon launching _Subsurface_
after using this software for a week or so, a one-box user survey pops up. It is entirely
optional and the user controls what, if any, data are sent to the _Subsurface_ development
team. Any data that the user chooses to send is extremely useful, and will only be
used to steer future development and to customise the software to fit the needs of
the _Subsurface_ users. If one completes the survey, or clicks the option not to
be asked again, that should be the last communication of this nature one receives.
However, if one's diving and/or subsurface habits change and one wishes to provide
another survey, this can be done by launching _Subsurface_ with the _--survey_ option on the
command line.

[[S_StartUsing]]
Start Using the Program
-----------------------

The _Subsurface_ window is usually divided into four panels with a *Main
Menu* (File Import Log View Help) at the top of the window (for Windows
and Linux) or the top of the screen (for Mac and Ubuntu Unity). The four panels are:

1. The *Dive List* to the bottom left containing a list of all the dives in the
user's
dive log. A dive can be selected and highlighted on the dive list by clicking on
it. In most situations the up/down keys can be used to switch
between dives. The *Dive List* is an important tool for manipulating a dive log.

2. The *Dive Map* to the bottom right, showing the user's dive sites on a world
map
and centred on the site of the last dive selected in the *Dive List*.

3. The *Info* to the top left, giving more detailed information on the
dive selected in the *Dive List*, including some statistics for the selected dive or for all
highlighted dive(s).

4. The *Dive Profile* to the top right, showing a graphical dive profile of the
selected dive in the *Dive List*.

The dividers between panels can be dragged in order to change the size of any of
the panels. _Subsurface_ remembers the position of the dividers, so the next
time _Subsurface_ starts it uses the positions of the dividers from when the program
was last used.

If a single dive is selected in the *Dive List*, the dive location, detailed information
and profile of
the _selected dive_ are shown in the respective panels. On the other hand, if
several dives are selected, the last highlighted dive is the _selected
dive_, but summary data of all _highlighted dives_ are shown in the *Stats* tab
of the *Info* panel (maximum, minimum and average depths, durations, water
temperatures and SAC; total time and number of dives selected).

[[S_ViewPanels]]

image::images/main_window_f22.jpg["The Main Window",align="center"]

The user can determine which of the four panels are displayed by selecting the
*View* option on the main menu. This feature gives the user several choices of
display:

*All*: show all four of the panels as in the screenshot above.

*Divelist*: Show only the Dive List.

*Profile*: Show only the Dive Profile of the selected dive.

*Info*: Show only the Notes about the last selected dive and statistics for
all highlighted dives.

*Globe*: Show only the world map, centred on the last selected dive.

Like many other functions that can be accessed via the Main Menu, these options
can be triggered using keyboard shortcuts. The shortcuts for a particular system
are shown with an underline in the main menu entries. Since different Operating
Systems and the user chosen language may cause _Subsurface_ to use different
shortcut keys they are not listed here in the user manual.

When the program is started for the first time, it shows no information at all.
This is because the program doesn't have any dive information available. In the
following sections, the procedures to create a new logbook will be described.

[[S_NewLogbook]]
Creating a new logbook
----------------------
Select _File ->  New Logbook_ from the main menu. All existing dive data are
cleared so that new information can be added. If there are unsaved data in an
open logbook, the user is asked whether the open logbook should be
saved before a new logbook is created.

[[S_GetInformation]]
== Storing dive information in the logbook

Now that a new logbook was created, it is simple to add dive data to it.
_Subsurface_ allows several ways of adding dive data to a logbook, detailed
in the following sections.

1) If the user has a handwritten divelog, a spreadsheet or another form of
 manually maintained divelog, dive data can be added to the logbook using
 one of these approaches:

 - Enter dive information by hand. This is useful if the diver did not
 use a dive computer and dives were recorded in a written logbook. See:
 xref:S_EnterData[Entering dive information by hand]

 - Import dive log information that has been maintained either as a spreadsheet
 or as a CSV file. Refer to: xref:S_Appendix_D[APPENDIX D: Exporting a spreadsheet to CSV format] and
 to xref:S_ImportingCSVDives[Importing dives in CSV format].

2) If one has dives recorded using a dive computer, the depth profile of the
 dive and a large amount of additional information can be accessed. These dives
 can be imported from:

 - The dive computer itself. See: xref:S_ImportDiveComputer[Importing new dive information from a Dive Computer] or

 - Proprietary software distributed by manufacturers of dive computers. Refer
 to: xref:S_ImportingAlienDiveLogs[Importing dive information from other digital data sources or other data formats].

 - Import from spreadsheet or CSV files containing dive profiles.
 See: xref:S_ImportingCSVDives[Importing dives in CSV format from dive computers or other dive log software]


[[S_EnterData]]
=== Entering dive information by hand

This is usually the approach for dives without a dive computer. The basic record
of information within _Subsurface_ is a dive. The most important information
in a simple dive logbook usually includes dive type, date, time, duration,
depth, the names of your dive buddy and of the dive master or dive guide, and
some remarks about the dive. _Subsurface_ can store much more information
than this for each dive. In order to add a dive to a dive log, select _Log
->  Add Dive_ from the Main Menu. The program then shows three panels to enter
information for a dive: two tabs in the *Info* panel (*Notes* and
*Equipment*), as well as the *Dive Profile* panel that displays a graphical profile
of each dive. These panels are respectively marked [red]#A#, [red]#B# and
[red]#C#
in the figure below. Each of these tabs will now be explained for data entry.

image::images/AddDive1_f22.jpg["FIGURE: Add dive",align="center"]

When one edits a field in Notes or Equipment panels, _Subsurface_ enters *Editing Mode*,
indicated by the message in the blue box at the top of the *Notes* panel (see the image below). This message is
displayed in all the panels under Notes and Equipment when in *Editing Mode*.

image::images/BlueEditBar_f22.jpg["Blue edit bar",align="center"]

The _Apply changes_ button should only be selected after all the parts of a dive have been entered.
When entering dives by hand, the _Info_, _Equipment_ and _Profile_ tabs should be completed
before saving the information. By selecting the _Apply changes_ button, a local copy of the information
for this specific dive is saved in memory. When one closes Subsurface, the program will
ask again, this time whether the complete dive log should be saved on disk or not.

[[S_CreateProfile]]
==== Creating a Dive Profile

The *Dive Profile* (a graphical representation of the depth of the dive as a
function of time) is indicated in the panel on the top right hand of the
_Subsurface_ window. When a dive is manually added to a logbook, _Subsurface_
presents a default dive profile that needs to be modified to best represent the
dive being described:

image::images/DiveProfile1_f20.jpg["FIGURE: Initial dive profile",align="center"]

_Modifying the dive profile_: When the cursor is moved around the dive profile,
its position is indicated by two right-angled red lines as shown below.
The time and depth
represented by the cursor are indicated at the top of the black information box
(@ and D). The units (metric/imperial) on the axes are determined by the
*Preference* settings. The dive profile itself comprises several
line segments demarcated by waypoints (white dots on the profile, as shown
above). The default dive depth is 15 m.
If the dive depth was 20 m then the user needs to drag the appropriate waypoints
downwards to represent 20 m. To add a waypoint, double-click on
any line segment. To move an additional waypoint, drag it.
To remove this waypoint, right-click on it and choose "Remove this point" from the
context menu. Drag the waypoints to represent an
accurate
time duration for the dive. Below is a dive profile for a dive
to 20 m for 30 min, followed by a 5 minute safety stop at 5 m.

image::images/DiveProfile2_f20.jpg["FIGURE: Edited dive profile",align="center"]

_Specifying the gas composition:_ The gas composition used is clearly indicated
along the line segments of the dive profile. This defaults to the first gas
mixture specified in the *Equipment* tab, which was air in the case of the
profile above. The gas mixtures of segments of the dive profile can
be edited. This is done by right-clicking on the particular
waypoint and selecting the appropriate gas from the context menu. Changing
the gas for a waypoint affects the gas shown in the segment _to the left_ of
that
waypoint. Note that only the gases defined in the *Equipment* tab appear in the
context menu (see image below).

image::images/DiveProfile3_f20.jpg["FIGURE: Gas composition context menu",align="center"]

With the profile having been defined, more details must be added in order to have
a fuller record of the dive. To do this,
the *Notes* and the *Equipment* tabs on the top left hand of the
_Subsurface_ window should be used. Click on
xref:S_Notes_dc[*this link*] for instructions to use these tabs.

[[S_ImportDiveComputer]]
=== Importing new dive information from a Dive Computer

==== Connecting and importing data from a dive computer.

The use of dive computers allows the collection of a large amount of
information about
each dive, e.g. a detailed record of depth, duration, rates of ascent/descent
and of gas partial pressures. _Subsurface_ can capture this information and
present it as part of the dive information, using dive
information from a wide range of dive computers. The latest list of supported
dive computers can be found at:
link:http://subsurface-divelog.org/documentation/supported-dive-computers/[
Supported dive computers].

[icon="images/icons/warning2.png"]
[WARNING]
Several dive computers consume more power when they are in their
PC-Communication mode. **This could drain the dive computer's battery**. We
therefore
recommend that the user checks if the dive computer is charged when
connected to the USB port of a PC. For example, several Suunto and Mares dive
computers do not recharge through the USB connection. Users should refer to
the dive computer's manual
if they are unsure whether the dive computer recharges its batteries
while connected to the USB port.

To import dive information from a dive computer to a computer with
_Subsurface_,
it is necessary that the two pieces of equipment communicate with one another.
This
involves setting up the communications port (or mount point) of the computer
with _Subsurface_ that communicates with the dive computer. In order to set up
this communication, one needs to find the appropriate information to
instruct
_Subsurface_ where and how to import the dive information.
xref:_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer[Appendix A]
provides the technical information to help the user achieving this for different
operating
systems and
xref:_appendix_b_dive_computer_specific_information_for_importing_dive_information[Appendix B]
has dive computer specific information.

After this, the dive computer can be hooked up to the user's PC, which can be
achieved by following these steps:

1. The interface cable should be connected to a free USB port (or the Infra-red
	or Bluetooth connection set up as described later in this manual)

2. The dive computer should be placed into PC Communication mode.
	(Refer to the manual of the specific dive computer)

3. In _Subsurface_, from the Main Menu, select _Import ->  Import
   From Dive Computer_.
   Dialogue *A* in the figure below appears:


image::images/DC_import_f20.jpg["FIGURE: Download dialogue 1",align="center"]

Dive computers tend to keep a certain number of dives in their memory, even
though these dives have already been imported to _Subsurface_. For that reason, if
the dive computer allows this,
_Subsurface_ only imports dives that have not been uploaded before. This makes
the download process faster on most dive computers and also saves battery power
of the dive computer (at least for those not charging while connected via USB).

 - The dialogue has two drop-down lists, *Vendor* and *Dive Computer*. On the
   *vendor* drop-down list select the make of the computer, e.g.
   Suunto, Oceanic,
   Uwatec, Mares. On the *Dive Computer* drop-down list, the model name of
   the dive computer must be selected, e.g. D4 (Suunto), Veo200 (Oceanic), or Puck
   (Mares).

 - The *Device or Mount Point* drop-down list contains the USB or Bluetooth port
   name that _Subsurface_ needs in order to communicate with the dive computer.
   The appropriate port name must be selected. Consult
   xref:_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer[Appendix A]
   and
   xref:_appendix_b_dive_computer_specific_information_for_importing_dive_information[Appendix B]
   for technical details on how to find the appropriate port information for a
   particular dive
   computer and, in some cases, how to do the correct settings to the operating
   system of the computer on which _Subsurface_ is running.

 - If all the dives on the dive computer need to be downloaded, check the
   checkbox _Force download of all dives_. Normally, _Subsurface_ only downloads
   dives after the date-time of the last dive in the *Dive List* panel. If one
   or more of your dives in _Subsurface_ have been accidentally deleted or if there
   are older dives that still need to be downloaded from the dive computer, this
   checkbox needs to be activated. Some dive computers (e.g. Mares Puck) do not provide
   a contents list to _Subsurface_ before the download in order to select only new dives.
   Consequently, for these dive computers, all dives are downloaded
   irrespective of the status of this check box.

 - If the checkbox _Always prefer downloaded dives_
   has been checked and, during download, dives with identical date-times exist on
   the dive computer and on the _Subsurface_
   *Dive List* panel, the dive in the _Subsurface_ divelog will be overwritten
   by the dive record from the dive computer.

 - The checkbox marked _Download into new trip_ ensures that, after upload, the downloaded dives
   are grouped together as a new trip(s) in the *Dive List*.

 - Do *not* check the checkboxes labelled _Save libdivecomputer logfile_ and
   _Save libdivecomputer dumpfile_. These are only used as diagnostic tools
   when problems with downloads are experienced (see below).

 - Then select the _Download_ button.
   With communication established, one can see how the data are
   retrieved from the dive computer.
   Depending on the make of the dive computer and/or number of recorded dives, this
   could take some time. Be patient. The _Download_ dialogue
   shows a
   progress bar at the bottom of the dialogue (for some dive computers the
   progress information could be inaccurate as we cannot determine how much
   downloadable data there is until all data have been downloaded). After successful download, Dialogue *B*
   in the figure above appears.
   After the dives have been downloaded, they appear in a tabular format on the right-hand
   side of the dialogue (see image *B*, above). Each dive comprises a row in the table, with the date, duration
   and depth shown. Next to each dive is a checkbox: check all the dives that need to
   be transferred to the *Dive List*. In the case of the image above, the last six dives are
   checked and will be transferred to the *Dive List*. Then
   click the _OK_ button at the bottom of the dialogue. All the imported dives appear
   in the *Dive List*, sorted by date and time. Disconnect and
   switch off the dive
   computer to conserve its battery power.



After this has been completed, select the OK button.
The checked dives are transferred to the *Dive List*.

 - If there is a problem in communicating with the dive computer, an error
   message will be shown, similar to this text: "Unable to open /dev/ttyUSB0 Mares
   (Puck Pro)". Refer to the text in the box below.


****
*PROBLEMS WITH DATA DOWNLOAD FROM A DIVE COMPUTER?*
[icon="images/icons/important.png"]
[IMPORTANT]
Check the following:

 - Is the dive computer still in PC-communication or
   Upload mode?

 - Is the battery of the dive computer fully charged? If not then the battery
   must be charged or replaced.

 - Is the connecting cable faulty? Does the cable work perfectly using other
   software? Has it worked before, or is this the first time the cable is being used? Are the contacts
   on the dive computer and the cable clean?

 - Consult
   xref:_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer[Appendix A]
   and make sure that the correct Mount Point
   was specified (see above).

 - On Unix-like operating systems, does the user have write permission to the
   USB port? If not, consult
   xref:_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer[Appendix A]

If the _Subsurface_ computer does not recognise the USB adaptor by
showing an appropriate device name next to the Mount Point, then there is a
possibility that the cable or USB adaptor is faulty. A faulty cable is the most
common cause of communication failure between dive computer and _Subsurface_
computer. It is also possible that the _Subsurface_ computer cannot interpret
the data. Perform a download for diagnostic purposes with the following
two check boxes checked in the download dialogue discussed above:

	Save libdivecomputer logfile
	Save libdivecomputer dumpfile

*Important*: These check boxes are only used when problems are encountered
during the download process: under normal circumstances they should not be checked.
When checking these boxes, the user is prompted to select a folder to
save the information to. The default folder is the one in which the _Subsurface_
dive log is kept.

*Important:* _After downloading with the above checkboxes
checked, no dives are added to the
*Dive List* but two files are created in the folder selected above_:

	subsurface.log
	subsurface.bin

These files should be send to the _Subsurface_ mail list:
_subsurface@subsurface-divelog.org_ with a
request for the files to be analysed. Provide the dive computer
make and model
as well as contextual information about the dives recorded on the dive computer.
****

[[S_Bluetooth]]
==== Connecting _Subsurface_ to a Bluetooth-enabled dive computer
[icon="images/icons/bluetooth.jpg"]

Bluetooth is becoming a more common way of communication between dive computers
and _Subsurface_, for instance, the Shearwater Petrel
Mk2 and the OSTC Mk3. _Subsurface_ provides a largely operating system independent
Bluetooth interface. Setting up _Subsurface_ for Bluetooth communication requires
four steps:

- Ensure that Bluetooth is activated on the host computer running _Subsurface_.
- Ensure that _Subsurface_ sees the Bluetooth adapter on the host computer.
- Ensure the Bluetooth-enabled dive computer is Bluetooth-discoverable and in PC upload mode.
- Ensure that _Subsurface_ is paired with the Bluetooth-enabled dive computer.

Select the Download dialogue by selecting
_Import -> Import from dive computer_ from the *Main Menu*. If one checks the
check box labelled _"Choose Bluetooth download mode"_, the dialogue below appears.

===== On Linux or MacOS:

image::images/DC_import_Bluetooth.jpg["FIGURE: Download Bluetooth",align="center"]

On the _Linux_ or _MacOS_ platforms the name
of the _Subsurface_ computer and its Bluetooth address are shown on the right-hand side, On the lefthand side, if the
computer has connected more than one local Bluetooth devices the user can use
the list box to indicate which one needs to connect to _Subsurface_.
The power state (on/off) of the Bluetooth adapter is shown below
the address and can be changed by checking the _Turn on/off_ check box.

If the Bluetooth address is not shown, then _Subsurface_ does not see the local
Bluetooth device. Ensure that the Bluetooth driver is installed correctly on the
_Subsurface_ computer and check if it can be used by other Bluetooth utilities like
_bluetoothctl_ or _bluemoon_. This achieves the first two steps above.

Ensure that the Bluetooth-enabled dive computer is in PC-upload mode and that it
is discoverable by other Bluetooth devices. Consult the manual of the dive
computer to perform this. Now the third item in the list above has been achieved.

Select the _Scan_ button towards the bottom left of the dialogue above. After
searching for a small amount of time, the dive computer should be listed
(perhaps as one of a number of Bluetooth devices) in the main list box on the
lefthand side of the dialogue (see image above). If this is not achieved, select
the _Clear_ button and then scan again for Bluetooth devices using the _Scan_
button. After performing these actions _Subsurface_ should see the dive computer.
The label of the discovered dive computer contains the name of the device, its
address and its pairing status. If the device is not paired and has a red
background colour, a context menu can be opened by selecting the item with a
right-click.
Select the the _Pair_ option and wait for the task to complete.

****
[icon="images/icons/important.png"]
[IMPORTANT]
Currently _Subsurface_ does not support Bluetooth pairing with dive
computers that require a custom PIN code. In order to pair the devices, use other
OS utilities as suggested below.

One way to achieve this is to use +bluetoothctl+:

	$ bluetoothctl
	[bluetooth]# agent KeyboardOnly
	Agent registered
	[bluetooth]# default-agent
	Default agent request successful
	[bluetooth]# pair 00:80:25:49:6C:E3
	Attempting to pair with 00:80:25:49:6C:E3
	[CHG] Device 00:80:25:49:6C:E3 Connected: yes
	Request PIN code
	[agent] Enter PIN code: 0000
****

After the devices are paired the _Save_ button of the dialogue can be pressed.
This closes the Bluetooth dialogue. Now select _Download_ in the _Download from
dive computer_ dialogue which should still be open. The downloaded dives are
shown on the righthand side of the download dialogue.

===== On Windows:
image::images/DC_import_Bluetooth_Windows.png["FIGURE: Download Bluetooth on Windows",align="center"]

On _Windows_ platforms the _Local Bluetooth device details section_ on the right is not displayed.
To successfully initiate a scan (by pressing the _Scan_ button)
check that the Bluetooth device on the _Subsurface_ computer is turned on.

The pairing step is checked and done automatically during
the download process. If the devices have never been paired the system will ask
for your permissions and put a message on the right side of the screen: _Add a
device, Tap to set up your DC device_. Always allow this pairing. After a
discovered item is selected, select the _Save_ button.
Finally select the _Download_ button on the _Download_ dialogue and wait for the process to complete.

[icon="images/icons/important.png"]
[IMPORTANT]
Be aware that currently _Subsurface_ works only with local Bluetooth
adapters which use Microsoft Bluetooth Stack. If the local device uses
_Widcomm_,  _Stonestreet One Bluetopia Bluetooth_ or _BlueSolei_ drivers it
will definitely not work.


A log messageOn the bottom left of the _Remote Bluetooth device selection_
shows details about the current status of the Bluetooth agent. To
select another dive computer for download using the "Remote Bluetooth selection dialogue"
press the three-dots button from the _"Choose Bluetooth download mode"_ option.

[icon="images/icons/important.png"]
[IMPORTANT]

*IN CASE OF PROBLEMS*:  If the Bluetooth adapter from the _Subsurface_ computer
gets stuck and the _Download_ process fails repeatedly,
 _unpair_ the devices and then repeat the above steps. If this is not successful,
 xref:S_HowFindBluetoothDeviceName[_Appendix A_] contains
information for manually setting up and inspecting the Bluetooth connection
with _Subsurface_.


[[S_DeviceNames]]
==== Changing the name of a dive computer

It may be necessary to distinguish between different dive computers used to
upload dive logs to _Subsurface_. For instance if one's partner's dive computer is the
same make and model as one's own and dive logs are uploaded from both dive computers
to the same _Subsurface_ computer, then
one would perhaps like to call one dc "Alice's Suunto D4" and the other one
"Bob's Suunto D4". Alternatively, consider a technical diver dives with two or more
dive computers of the same model, the logs of both (or all) being uploaded.
In this case it might be prudent to call one of them
"Suunto D4 (1)" and another one "Suunto D4 (2)". This is easily done in _Subsurface_.
On the *Main Menu*, select _Log ->  Edit device names_. A dialog opens, indicating the
current Model, ID and Nickname of the dive computers used for upload. Edit the Nickname
field for the appropriate dive computer. After saving the Nickname, the dive logs
show the nickname for that particular device instead of the model name,
allowing easy identification of devices.

[[S_EditDiveInfo]]
==== Updating the dive information imported from the dive computer.

With the uploaded dives in the *Dive List*, the information from the dive
computer is not complete and more details must be added in order to have
a fuller record of the dives. To do this,
the *Notes* and the *Equipment* tabs on the top left hand of the
_Subsurface_ window should be used.

[[S_Notes_dc]]
===== Notes

To have a more complete dive record the user needs to add
additional information by hand. The procedure
below is virtually identical for hand-entered dives and for dives downloaded from a dive computer.

In some cases,
one has to provide the date and time of the dive, e.g. when entering a dive by hand or when a
dive computer does not provide the date and time of the dive.
(Usually the date and time of the dive, gas mixture and water temperature are
shown as obtained from the dive computer)
If the contents of the *Notes tab* is changed or edited in any way, the message in a blue box at
the top of the panel indicates that the dive is being edited. If one
clicks on the *Notes* tab, the following fields are
visible (left hand image, below):

image::images/AddDive3_f22.jpg["FIGURE: The Notes tab",align="center"]

The right hand image, above, shows a *Notes tab* filled with dive information.
The *Time* field reflects the date and time of the dive. By clicking
the date, a calendar is displayed from which
one can choose the correct date. Press ESC to close the calendar.
The time values (hour and minutes) can also be
edited directly by clicking on each of them in the text box and by over-typing the
information displayed.

*Air/water temperatures*: Air and water temperatures during the dive are shown
in text boxes to the right of the Start time. Many dive computers supply water
temperature information and this box may therefore contain information.
If air temperature is not provided by the dive computer, the first temperature reading
might be used for the air temperature. Generally this is close enough to the real air temperature as
the change in the temperature sensor reading is quite slow to follow the changes in the environment.
If editing is required, only a value is required, the units of temperature will be
automatically supplied by
_Subsurface_ (following the _Preferences_, metric or imperial units will
be used).

*Location*:
[icon="images/icons/warning2.png"]
[WARNING]
Dive locations are managed as a *separate* part of the dive log.
The dive information in the *Notes* and *Equipment* tabs can therefore not be edited at the same
time as the dive site information. Save all the other dive information (e.g.
divemaster, buddy, protective gear, notes about the dive) by selecting _Apply changes_ on the
*Notes* tab before editing the dive site information. Only then, supply a dive site name in the
textbox labelled _Location_ on the *Notes* tab.

Type the name of the dive site, e.g. "Tihany, Lake Balaton, Hungary".
If several dives are
performed at the same location, the dive site information for the first dive is re-used.
Existing dive location information
can be edited at any time by selecting (on the *Dive List* panel) a dive performed at that site
and by opening the location information by clicking the globe button on the
right of the location name (see image on the right, above). When entering a dive location name, auto location of
dive site names makes it easy to select an existing dive site name
(i.e. when typing the name of a dive site,
a dropdown list appears showing all sites with similar names). If the dive
site has been used before, click on the already-existing name.
The dive site names in the dropdown list contain either a globe symbol (indicating
existing dive sites in the _Subsurface_ database)
or a *+* symbol (indicating dive site names that appear consistent with the
current dive site name but which have not been added to the dive site database).
Therefore, if the present
dive site has not been used before, a message appears as follows (image *A* below):

image::images/Locations1_f22.jpg["FIGURE:Location description panel",align="center"]

Doubleclick on the new dive site name. A panel appears to enter the coordinates and
other important information about the site (image *B*, above). The most important
items are the coordinates of the site. There are three ways of specifying the coordinates:

a. One can find the coordinates on the world map in the bottom right hand
   part
   of the _Subsurface_ window. The map displays an orange bar indicating "No location
   data - Move the map and double-click to set the dive location". Upon a doubleclick
   at the appropriate place, the orange bar disappears and the coordinates are
   stored.

b. The coordinates can be obtained from the _Subsurface_ Companion app if the
   user has an Android or iPhone device with GPS and if the coordinates of the dive site
   were stored using that device.
   xref:S_Companion[Click here for more information]

c. The coordinates can be entered by hand if they are known, using one of
   four formats with latitude followed by longitude:

	ISO 6709 Annex D format e.g. 30°13'28.9"N 30°49'1.5"E
	Degrees and decimal minutes, e.g. N30° 13.49760' , E30° 49.30788'
	Degrees minutes seconds, e.g. N30° 13' 29.8" , E30° 49' 1.5"
	Decimal degrees, e.g. 30.22496 , 30.821798

Southern hemisphere latitudes are given with a *S*, e.g. S30°, or with a
negative value, e.g. -30.22496. Similarly western longitudes are given with a
*W*, e.g. W07°, or with a negative value, e.g. -7.34323. Some keyboards
don't have the degree sign (°). It can be replaced by a *d* like this: N30d W20d.
If both a dive site name and coordinates have been provided, Save the
dive site information by selecting the button _Apply changes_ at the top of
the panel.

*Important*: GPS coordinates of a dive site are linked to the Location
name - so *saving* a dive site with only coordinates and no dive site name
causes unexpected behaviour (Subsurface will think that all of these
dives have the same location and try to keep their GPS coordinates the
same).

*Dive site name lookup:* If coordinates have been typed into the appropriate
text box, one can perform an automated name lookup based on the coordinates.
This is achieved when _Subsurface_ uses the Internet to find the name of the dive site
based on the coordinates that were typed. If a name has been found, it is
automatically inserted into the tags box. The list box
(Titled _Dive sites on same coordinates_") at the bottom
of the dive site panel contains the names of other dives sites used at the
current location. For instance if the dive site is "Blue Hole" and there are several
dive sites named "Blue Hole", all these sites are listed in this list box.

Enter any other textual information about the dive site (Description and Notes),
then select _Apply Changes_ to save the geolocation for this dive site. At a later stage
the dive site information can be edited by clicking the globe icon to the right of the
dive site name in the *Notes tab*.

*Dive mode*: This is a dropdown box allowing one to choose the type of dive
performed. The options are OC (Open Circuit SCUBA, the default seting, meant for most recreational dives),
Freedive (dive without SCUBA equipment), CCR (Closed-circuit
rebreather) and pSCR (Passive semi-closed rebreather).

*Divemaster*: The name of the dive master or dive guide for this dive should be
entered in this field
which offers auto selection based on the list of dive masters in
the current logbook.

*Buddy*: In this field, one enters the name(s) of the buddy / buddies
(separated with commas) who accompanied him/her on the
dive. Auto selection based on the list of buddies in the current logbook is
offered.

*Suit*: Here the type of dive suit used can be entered.
Auto selection of the suit description is available.
Some dry-suit users may choose to use this field to record what combination of
suit and thermal undersuit was used.

*Rating*: One can provide a subjective overall rating of the dive on a
5-point scale by clicking the appropriate star on the rating scale.

*Visibility*: Similarly, one can provide a rating of visibility during the
dive on a
5-point scale by clicking the appropriate star.

*Tags*: Tags that describe the type of dive performed can be entered
here (separated by commas). Examples of common tags are boat, drift, training,
cave, etc.
_Subsurface_ has many built-in tags. If the user starts typing a tag, the
program
will list the tags that correspond to the typing. For instance, if the user
typed
+cav+, then the tags *cave* and *cavern* are shown for the user to choose from.

*Notes*: Any additional information for the dive can be entered here.

The _Apply changes_ and _Discard changes_ buttons are used to save all the information for tabs
in the *Info* panel and in the *Dive Profile* panel, so there's no need to use them
until *ALL* other information has been added. The image xref:S_Notes_dc[at the beginning of this section]
shows an example of a *Notes tab* after completion of the dive information.

===== Equipment

The Equipment tab allows one to enter information about the type of
cylinder and gas used as well as the weights used for the dive. The
message in a blue box at the top of the panel:

image::images/BlueEditBar_f22.jpg["FIGURE: Blue edit bar",align="center"]

indicates that the dive is being edited. This is a highly interactive part of
_Subsurface_ and the information on
cylinders and gases (entered here) determines the behaviour of the *Dive profile*
(top right-hand panel).

[[cylinder_definitions]]
*Cylinders*: The cylinder information is entered through a dialogue that looks
like this:

image::images/DC_gas-dialogue1_f20.jpg["FIGURE: Initial cylinder dialogue",align="center"]

For hand-entered dives, this information needs to be typed in. For dive computers,
_Subsurface_ often obtains the gas used from the dive computer and
automatically inserts the gas composition(% oxygen or % helium) in the table. The + button
at the top right allows the user to add more cylinders for this dive. The dark
dustbin icon on the left allows the deletion of information for a cylinder.
Note that it is not possible to delete a cylinder if it is used during the
dive. A cylinder might be implicitly used in the dive, even without a gas change event.

The user should start by selecting a cylinder type on the left-hand side of the
table.  To select a cylinder, the _Type_ box should be clicked. This
brings up a list button that can be used to display a dropdown list of
cylinders:

image::images/DC_gas-dialogue2_f20.jpg["FIGURE: The cylinder drop-down list button",align="center"]

The drop-down list can then be used to select the cylinder type that was used
for this dive or the user may start typing in the box which shows the available
options for the entered characters. The
*Size* of the cylinder as well as its working pressure (_Work.press_) will
automatically be shown in the dialogue.

Next, indicate the starting pressure and the ending pressure of the
specified gas during the dive. The unit of pressure (metric/imperial)
corresponds to the settings chosen in the _Preferences_.

Finally, provide the gas mixture used. If air was used, the
value of 21%  can be entered  or this field can be left blank. If nitrox or
trimix were used, their percentages of oxygen and/or helium should be entered.
Any inappropriate fields should be left empty. After typing the
information for the cylinder, save the data
either by pressing _ENTER_ on the keyboard or by clicking outside the cell
containing
the cursor. Information for any additional cylinders can be added by using the +
button at the top right hand. Following is an example of a complete description
for a dive using two cylinders (air and EAN50):

image::images/CylinderDataEntry3_f20.jpg["FIGURE: a completed cylinder dive information table",align="center"]

*Weights*: Information about the weight system used can be entered
using a dialogue very similar to that of the cylinder information. If one
clicks
the + button on the top right of the weights dialogue, the table looks like
this:

image::images/WeightsDataEntry1_f20.jpg["FIGURE:The Weights dialogue",align="center"]

By clicking on the _Type_ field, a drop-down list becomes accessible through a
down-arrow:

image::images/WeightsDataEntry2_f20.jpg["FIGURE:Weights type drop-down list button",align="center"]
This can be used to select the type of weight system
used during the dive or the user may start typing in the box
to specify a different weighting mechanism that will be saved by _Subsurface_.
In the *Weight*
field, type in the amount of weight used during the dive. After
specifying the weight
system, save the data by either pressing _ENTER_ on the keyboard or by clicking outside the
cell with the cursor.
It is possible to enter information for more than one weight system by adding
an additional system
using the + button on the top right hand. Weight systems can be deleted using
the dustbin icon on the left hand. Here is an example of information for a dive
with two types of weights: integrated as well as a weight belt:

image::images/WeightsDataEntry3_f20.jpg["FIGURE: A completed weights information table",align="center"]

==== Editing several selected dives simultaneously

_METHOD 1_: After uploading dives from
a dive computer, the dive profiles of each uploaded dive is shown in the *Dive profile* tab, as well
as a few items of information
in the *Notes* tab (e.g. water temperature) and in the *Equipment* tab (e.g. gas pressures
and gas composition). However the other fields remain empty.
It may be useful to simultaneously edit some of the
fields in the *Notes* and *Equipment* tabs.  For instance, it is possible
that a diver performed several dives during a single day, using identical equipment while diving at the same
dive site or with the same dive master and/or buddy or tags. Instead of completing the information for each
of these dives separately, one can select all the dives for that day in the *Dive List* and
insert the same information in the *Notes* and *Equipment* fields that need
identical information. This is achieved by editing the dive notes or the equipment for any one
of the selected dives.

The simultaneous editing only works with fields that do not already contain information.
This means that, if some fields have been edited for a particular dive among the selected dives,
these are not changed while
editing the dives simultaneously. Technically, the rule for editing several dives simultaneously is:
if the data field being edited contains _exactly the same information_ for all the dives that have been
selected, the new, edited information is substituted for all the selected dives, otherwise only the
edited dive is
changed, even though several dives have been selected in the *Dive List*. This greatly speeds
up the completion of the dive log after several similar dives.

[[S_CopyComponents]]
_METHOD 2_:There is a different way of achieving the same goal. Select a dive with all the appropriate information
typed into the *Notes* and *Equipment* tabs. Then, from the main menu, select _Log ->  Copy dive components_.
A box is presented with a selection of check boxes for most of the fields in the *Notes* and *Equipment* tabs.
Select the fields to be copied from the currently selected dive, then select _OK_. Now, in the *Dive List*,
select the dives
into which this information is to be pasted. Then, from the main menu, select _Log ->  Paste dive components_.
All the selected dives now contain the data initially selected in the original source dive log.

==== Adding Bookmarks to a dive

Many divers wish to annotate their dives with text that indicate particular events
during the dive, e.g. "Saw dolphins", or "Released surface buoy". This is easily
done:

 - Right-click at the appropriate point on the dive profile.
   This brings up the dive profile context menu. Select _Add bookmark_. A red flag is
   placed on the dive profile at the point that was initially selected (see *A* below).

 - Right-click on the red flag. This brings up the context menu (see *B* below). Select _Edit name_.

 - A text box is shown. Type the explanatory text for the bookmark (see *C* below). Select _OK_.
   This saves the text associated with the bookmark.

 - If one hovers using the mouse over the red bookmark, the appropriate text is shown at
   the bottom of the information box (see *D* below).

image::images/Bookmarks.jpg["FIGURE: Bookmark dialog",align="center"]


==== Saving the updated dive information

The information entered in the *Notes* tab and the *Equipment* tab can be
saved by using the
two buttons on the top right hand of the *Notes* tab. If the _Apply changes_ button
is clicked,
the dive data are saved in the memory image of the dive. If the _Discard changes_
button is clicked, then the newly entered dive data are
erased from the computer memory, although the dive profile is
retained. When the user exits _Subsurface_ there is a final prompt to confirm
that the new data should now be saved permanently on the computer disk.

=== Importing dive information from other digital data sources or other data formats

[[S_ImportingAlienDiveLogs]]

If a user has been diving for some time, it is possible that several dives were
logged using other dive log software. This information does not need retyping
because these dive logs can probably be
imported into _Subsurface_. _Subsurface_ will import dive logs from a range of
other
dive log software. While some software is supported natively, for others the
user has to
export the logbook(s) to an intermediate format so that they can then be imported
by _Subsurface_.
Currently, _Subsurface_ supports importing CSV log files from several sources.
APD LogViewer, XP5, Sensus and Seabear files are
preconfigured, but because the import is flexible, users can configure their own
imports.
Manually kept log files (e.g. a spreadsheet) can also be imported by
configuring the CSV import.
_Subsurface_ can also import UDDF and UDCF files used by some divelog
software and some dive computers, like the Heinrichs & Weikamp DR5. Finally,
for some divelog software like Mares Dive Organiser it is currently suggested to
import the logbooks first into a webservice like _divelogs.de_ and then import
them from there with
_Subsurface_, as divelogs.de supports a few additional logbook formats that
_Subsurface_ currently cannot parse.

If the format of other software is supported natively on Subsurface, it should be sufficient to select
either _Import ->  Import log files_ or _File ->  Open log file_. _Subsurface_ supports the data formats
of many dive computers, including Suunto and Shearwater. When importing dives, _Subsurface_
tries to detect multiple records for
the same dive and merges the information as best as it can. If
there are no time zone issues (or other reasons that would cause the
beginning time of the dives to be significantly different) _Subsurface_
will not create duplicate entries. Below follows more specific information
to achieve data import to _Subsurface_.

==== Using the universal import dialogue
[[Unified_import]]

Importing dives from other software is performed through a universal interface
activated by selecting _Import_ from the Main Menu, then clicking on
_Import Log Files_. This brings up dialogue *A*, below.

image::images/Import1_f20.jpg["FIGURE: Import dialogue: step 1",align="center"]

Towards the bottom right is a dropdown selector with a default label
of _Dive Log Files_ which gives access to the different types of direct imports
available, as in dialogue *B*, above. Currently these are:

 - XML-formatted dive logs (DivingLog 5.0, MacDive and several other dive log systems)
 - Cochran dive logs
 - UDDF-formatted dive logs (e.g. Kenozoooid)
 - UDCF-formatted dive logs
 - Poseidon MkVI CCR logs
 - APD Inspiration/Evolution CCR logs
 - LiquiVision logs
 - divelog.de logs
 - OSTC Tools logs
 - JDiveLog
 - Suunto Dive Manager (DM3 and DM4)
 - CSV (text-based and spreadsheet-based) dive logs, including APD CCR logs

Selecting the appropriate format and then the specific log file in the large window
containing the file list on the right of the dialogue opens
the imported dive log in the _Subsurface_ *Dive List*. Some other formats, not
accessible through the Import dialogue are also supported, as explained below.

==== Importing from  OSTCTools

_OSTC Tools_ is a Microsoft-based suite of dive download and dive management tools for the OSTC
family of dive computers. _OSTC Tools_ downloads dive data from the dive computer and stores it
as a binary file with file extension _.dive_ . Subsurface can directly import these files when using
the universal import dialogue. From the dropdown list at the bottom right select
_OSTCTools Files (.dive .DIVE)_. This makes the _OSTC Tools_ dive logs visible in the file list
panel. Select one or more dive, then click the _Open_ button. The OSTC dives are shown in the
*Dive List* panel.

Actually, all H&W devices supported by OSTCTools can be imported to _Subsurface_, this includes
OSTC, OSTC Mk2, OSTC 2N/2C, OSTC3, OSTC Sport, and probably although untested, Frog, OSTC2 and
OSTC CR.

Please, remember that OSTCTools is *not* a true diving log software, but a useful set of tools
for analysis and management of OSTC devices. This way, only raw dive computer data will be
performed with the import to _Subsurface_; one has to to manually complete the rest of
data which may be important (buddies, equipment, notes, etc).


==== Importing from Mares Dive Organiser V2.1

Since Mares utilise proprietary Windows software not compatible with
multi-platform applications, these dive logs cannot be
directly imported into
_Subsurface_. Mares dive logs need to be imported using a three-step process,
using _www.divelogs.de_ as a mechanism to extract the dive log information.

1. Export the dive log data from Mares Dive Organiser to the user's
   desktop, using
   a _.sdf_ file name extension. Refer to xref:Mares_Export[Appendix C] for more
   information.
2. Data should then be imported into _www.divelogs.de_. One needs to create a user
   account in
   _www.divelogs.de_, log into that web site, then
   select _Import Logbook ->  Dive Organiser_ from the menu on the left hand side.
   The instructions must be carefully followed to transfer the dive information
   (in _.sdf_ format) from the Dive Organiser database to _www.divelogs.de_.
3. Finally,  import the dives
   from _divelogs.de_ to _Subsurface_, using the instructions below.


[[S_ImportingDivelogsDe]]
==== Importing dives from *divelogs.de*

The import of dive information from _divelogs.de_ is simple, using a single
dialogue box. The _Import ->  Import from Divelogs.de_ option should be selected
from the Main Menu. This
brings up a dialogue box (see image *A* below). Enter a
user-ID and password for _divelogs.de_ into the appropriate fields and then
select
the _Download_ button. Download from _divelogs.de_ starts immediately,
displaying a progress bar in the dialogue box. At the end of the download, the
success status is indicated (see image *B*, below). The
_Apply_ button should then be selected, after which the imported dives appear in the
_Subsurface_ *Dive List* panel.

image::images/Divelogs1.jpg["FIGURE:Download from Divelogs.de",align="center"]

[[S_ImportingCSVData]]
==== Importing data in CSV format

A comma-separated file (.csv) can be used to import dive information either as dive profiles
(as in the case of the APD Inspiration and Evolution closed circuit rebreathers) or as dive
metadata (in case the user keeps dive data in a spreadsheet). The _CSV_ format is a universal
simplified format that allows for easy information exchange between different computers or
software packages. For an introduction to CSV-formatted files see xref:S_CSV_Intro[A Diver's
Introduction To CSV Files]. _Subsurface_ dive logs can also be exported in _CSV_ format to
other software that reads this format. See xref:S_Appendix_D[APPENDIX D: Exporting a spreadsheet
to CSV format] for information that may be helpful for importing spreadsheet-based data
into _Subsurface_.

[[S_ImportingCSVDives]]
===== Importing dives in CSV format from dive computers or other dive log software

One can view a _CSV_ file by using an ordinary text editor. It is normally organised into
a single line that provides the headers (or _field names_ or _column headings_) of the data
columns, followed by the data, one record per line.

There are two types of _CSV_ dive logs that can be imported into _Subsurface_:

1. _CSV dive details_: This dive log format contains similar information to that of a
   typical written dive log, e.g. dive date and time, dive depth, dive duration, names of
   buddy and dive master and perhaps some information about cylinder pressures before and
   after the dive, as well as a comment or two about the dive. All the data for a single
   dive go on a single line of text, following the order of the column headings.

2. _CSV dive profile_: This dive log format includes much more information about a single
   dive. For instance there may be information at 30-second intervals, indicating depth, water
   temperature at that depth, and cylinder pressure at that moment in time. Each line contains
   the information for a single instant in time during the dive, 30 seconds after that
   of the previous instant. Many lines
   are required to complete the depth profile information for a single dive. This is a common
   export format used by closed-circuit rebreather (CCR) dive equipment and many software
   packages that handle dive computer data and/or dive logs.

Before being able to import the _CSV_ data to _Subsurface_ *one needs to know a few
things about the data being imported*:

a. Which character separates the different columns within a single line of
   data? This field separator should be either a comma (,) a semicolon (;) or a TAB character.
   This can be determined by opening the file with a text editor. If it is
   comma-delimited or semicolon-delimited, the comma or semicolon
   characters between the values are clearly visible. If these are not evident and
   the numbers are aligned in columns,
   the file is probably TAB-delimited (i.e. it uses a TAB as a field separator).

b. Which data columns need to be imported into _Subsurface_? Is it a _CSV dive details_
   file or a _CSV dive profile_ file? Open the file using a text editor and note
   the titles of the columns to be imported and their column positions.

c. Is the numeric information (e.g. dive depth) in metric or in imperial units?

Armed with this information, importing the data into _Subsurface_ is
straightforward. Select
_Import ->  Import Log Files_ from the main menu. In the resulting file
selection menu, select _CSV files_ (towards the bottom right). This shows all .CSV files in the selected
directory. Select the file that needs to be imported. A configuration panel
appears as depicted below:

image::images/csv_import1_f20.jpg["FIGURE: CSV download dialogue 1",align="center"]

Notice that, at the top left, there is a dropdown list containing pre-configured
settings for some of the more common dive computers and software packages
encountered by divers. If the _CSV_ file being imported originated from any of
these pre-configured items, then select it. Otherwise use the _Manual Import_
option. The configuration panel also has dropdown lists for the specification of the appropriate
field separator (Tab, comma or semicolon), the date format used in the _CSV_ file,
the time units (seconds, minutes or minutes:seconds), as well as the unit system
(metric or imperial). Selecting the appropriate options among these is critical for
the successful import of the data.

The last remaining task is to ensure that all the data columns have the appropriate
column headings. The top blue row of the data table contains the column
headings found in the _CSV_ data file. The blue row of balloons immediately above these
contains the names understood by _Subsurface_. These balloons can be moved using a drag-and-drop action. For
instance, _Subsurface_ expects the column heading for Dive number (" # ") to be "Dive # ". If
the column heading that _Subsurface_ expects is not in the blue row, then drag the
appropriate balloon from the upper area and drop it in the appropriate blue
cell at the top of the table. To indicate the correct column for "Dive #", drag
the ballooned item labelled "Dive # " and drop it in the blue
cell immediately above the white cell containing " # ". This is depicted in
the image below.

image::images/csv_import2_f20.jpg["FIGURE: CSV download dialogue 2",align="center"]

Continue in this way to ensure that all the column headings in the blue row of
cells correspond to the headings listed in the top part of the dialogue. Having
completed this task, select the _OK_ button to the bottom right of the dialogue.
The data from the _CSV_ file are imported and shown in the *Dive List* panel.

[[S_CSV_Intro]]
****
*A Diver's Introduction to _CSV_ Files*
[icon="images/icons/important.png"]
[IMPORTANT]

_CSV_ is an abbreviation for a data file format: _Comma-Separated Values_. It is a
file format allowing someone to view or edit the information using a text editor such
as Notepad (Windows), gedit (Linux) or TextWrangler (OS/X). The two main advantages of
the _CSV_ format is that the data are easily editable as text without any proprietary software
and ensuring all information is human-readable, not being obscured by any custom or
proprietary attributes that proprietary software insert into files.
Because of its simplicity the _CSV_ format is used
as an interchange format between many software packages, e.g. between
spreadsheet, statistical, graphics, database and diving software. Within _Subsurface_, _CSV_ files can also
be used to import information from other sources such as spreadsheet-based dive logs and
even from some dive computers.

_CSV_ files can be created or edited with a normal text editor. The most important attribute of a
_CSV_ file is the _field separator_, the character used to separate fields within a single line. The
field separator is frequently a comma, a colon, a SPACE character or a TAB character. When exporting data from
spreadsheet software, the field separator needs to be specified in order to create the _CSV_ file. _CSV_ files are
normally organised into a single line that provides the headers (or _field names_) of the data columns,
followed by the data, one record per line. Note that each field name
may comprise more than one word separated by spaces; for instance _Dive site_, below. Here is an example of
dive information for four dives using a comma as a field separator:

	Dive site,Dive date,Time,Dive_duration, Dive_depth,Dive buddy
	Illovo Beach,2012-11-23,10:45,46:15,18.4,John Smith
	Key Largo,2012-11-24,09:12,34:15,20.4,Jason McDonald
	Wismar Baltic,2012-12-01,10:13,35:27,15.4,Dieter Albrecht
	Pulau Weh,2012-12-20,09:46,55:56,38.6,Karaeng Bontonompo

The above data are not easily read by a human. Here is the same information in TAB-delimited format:

	Dive site	Dive date	Time	Dive_duration	Dive_depth	Dive buddy
	Illovo Beach	2012-11-23	10:45	46:15	18.4	John Smith
	Key Largo	2012-11-24	09:12	34:15	20.4	Jason McDonald
	Wismar Baltic	2012-12-01	10:13	35:27	15.4	Dieter Albrecht
	Pulau Weh	2012-12-20	09:46	55:56	38.6	Karaeng Bontonompo

It is clear why many people prefer the TAB-delimited format to the comma-delimited format. The
disadvantage is that one cannot see
the TAB characters. For instance, the space between _Dive_ and _date_ in the top line may be
a SPACE character or a TAB character (in this case it is a SPACE character: the tabs are before and
after _Dive date_). If the field names in the first line are long, the alignment with data in the other lines
cannot be maintained. Here is a highly simplified and shortened TAB-delimited example of a _CSV_ dive log
from an APD closed-circuit rebreather (CCR) dive computer:

	Dive Time (s)	Depth (m)	pO₂ - Setpoint (Bar) 	pO₂ - C1 Cell 1 (Bar)	Ambient temp. (Celsius)
	0       0.0     0.70    0.81    13.1
	0       1.2     0.70    0.71    13.1
	0       0.0     0.70    0.71    13.1
	0       1.2     0.70    0.71    13.2
	0       1.2     0.70    0.71    13.1
	10      1.6     0.70    0.72    12.7
	20      1.6     0.70    0.71    12.6
	30      1.7     0.70    0.71    12.6
	40      1.8     0.70    0.68    12.5

When a _CSV_ file is selected for import, _Subsurface_ displays the column headers as well as some of the data
in the first few lines of the _CSV_ file, making it much easier to work with _CSV_ files.
_CSV_ files can therefore be used in many contexts for importing data into a _Subsurface_ dive log.
Knowledge of a few basic things about the content of the _CSV_ file allows a smooth import
of the dives into _Subsurface_.

****


[icon="images/icons/important.png"]
[IMPORTANT]
The _CSV_ import has a couple of caveats. One should avoid some special characters
like ampersand (&), less than (<), greater than (>) and double quotes (") as part
of the numbers or text within a cell. The
file should use UTF-8 character set, if using non-ASCII characters. Also the
size of the _CSV_ file might cause problems. Importing 100 dives at a time
(_CSV dive details_) works, but larger files might exceed
the limits of the parser used. When encountering problems with _CSV_ imports, first try with
a smaller file to make sure everything works.


[[S_Companion]]
=== Importing GPS coordinates with the _Subsurface Companion App_ for mobile phones

Using the *Subsurface Companion App* on an _Android device_   or
xref:S_iphone[_iPhone_] with GPS, the coordinates
for the diving
location can be automatically passed to the _Subsurface_
dive log. The Companion App stores the dive locations on
a dedicated Internet file server. _Subsurface_, in turn, can collect
the localities from the file server.

To do this:

==== Create a Companion App account

- Register on the http://api.hohndel.org/login/[_Subsurface companion web page_].
  A confirmation email with instructions and a personal *DIVERID* will be sent,
  a long number that gives access to the file server and Companion App capabilities.

- Download the app from
  https://play.google.com/store/apps/details?id=org.subsurface[Google Play Store]
  or from
  http://f-droid.org/repository/browse/?fdfilter=subsurface&fdid=org.subsurface[F-Droid].

==== Using the Subsurface companion app on an Android smartphone

On first use the app has three options:

* _Create a new account._  Equivalent to registering in _Subsurface_ companion
  page using an Internet browser. One can request a *DIVERID* using this option,
  but this is supplied via email and followed up by interaction with the
  http://api.hohndel.org/login/[_Subsurface companion web page_] in order to
  activate the account.

* _Retrieve an account._  If users forgot their *DIVERID* they will receive an email
  to recover the number.

* _Use an existing account._ Users are prompted for their *DIVERID*. The app saves
  this *DIVERID* and does not ask for it again unless one uses the _Disconnect_ menu
  option (see below).

[icon="images/icons/important.png"]
[IMPORTANT]
In the _Subsurface_ main program, the *DIVERID* should also be entered on the
Default Preferences
panel, obtained by selecting _File ->  Preferences ->  Defaults_ from the main menu
in _Subsurface_ itself.
This facilitates synchronisation between _Subsurface_ and the Companion App.

===== Creating new dive locations

Now one is ready to get a dive position and
send it to the server. The Android
display will look like the left hand image (*A*) below, but without any dives.

Touch the "+" icon on the top right to add a new dive site, a menu will be
showed with 3 options:

* Current: A prompt for a place name (or a request to activate the GPS if it is turned
  off) will be displayed, after which the current location is saved.

* Use Map: This option allows the user to fix a position by searching a world map. A
  world map is shown (see *B* below) on which one should indicate the desired position
  with a _long press_ on the touch
  sensitive screen (if the marked location is erroneous, simply indicate a new location)
  and select the check symbol in the upper right. A dialog is shown allowing to enter the
  name of the dive location and the date-time of the dive (see *C* below). In order to import this
  dive location in _Subsurface_ it's advisable to set the time to agree with the time of
  that dive on the dive computer.

image::images/Companion_5.jpg["FIGURE: Companion App, add location using map",align="center"]


* Import local GPX file: The android device searches for .gpx files and located
  archives will be shown. The selected .gpx file is opened and the stored
  locations shown. Now one needs to select the appropriate locations, then select the
  tab in the upper right, after which the locations will be sent to the web service
  and added to the list on the Android device.

===== Dive lists of dive locations

The main screen shows a list of dive locations, each with a name, date and
time (see *A* below). Some locations may have an arrow-up icon over the selection box to the left
indicating that they require upload to the server. One
can select individual dive locations from the list. A selected location has a
check mark in the selection box on the left. Group operations (such as _Delete_ or _Send_)
are performed on several locations that are selected.

Dive locations in this list can be viewed in two ways: a list of locations or a
map indicating the dive locations. The display mode (List or Map) is changed by
selecting _Dives_ at the top left of the screen (see *A* below) and then selecting
the display mode. The display mode can be changed either from the list
of locations or from the map (see *B* below). If one selects a location (on the list
or on the map), an editing
panel opens (see *C* below) where the dive description or other details may be changed.

image::images/Companion_4.jpg["FIGURE: Companion App, add location using map",align="center"]


When one selects a dive (*not* selecting the check box), the
name given to it, date/time and GPS coordinates will be shown, with two options at the top
of the screen:

- Edit (pencil):  Change the text name or other characteristics of the dive location.

- Maps:  Display a map showing the dive location.

After editing and saving a dive location (see *C* above), one needs to upload it to the web
service, as explained below.

===== Uploading dive locations

There are several ways to send locations to the server.
The easiest is by simply
selecting the locations (See *A* below) and then touching the right arrow at the
top right of the screen.

[icon="images/icons/important.png"]
[IMPORTANT]
Users must be careful, as the trash icon on the right means exactly what it should;
it deletes the selected dive location(s).

image::images/Companion_1.jpg["FIGURE: Screen shots (A-B) of companion app",align="center"]


After a dive trip using the Companion App, all dive locations are ready to be
downloaded to a _Subsurface_ dive log (see below).


===== Settings on the Companion App

Selecting the _Settings_ menu option results in the right hand image above (*B*).

===== Server and account

- _Web-service URL._ This is predefined (http://api.hohndel.org/)

- _User ID._ The DIVERID obtained by registering as described above. The easiest way to
  obtain it is simply to copy and paste from the confirmation email but, of
  course, users can also type this information.

===== Synchronisation

- _Synchronize on startup_. If selected, dive locations in the Android device and those
  on the web service synchronise each time the app is started.

- _Upload new dives._ If selected, each time the user adds a dive location it is
  automatically sent to the server.

===== Background service
Instead of entering a unique dive location, users can leave the service running
in the background of their Android device, allowing the continuous collection of GPS locations.


The settings below define the behaviour of the service:

- _Min duration._ In minutes. The app will try to get a location every X minutes
  until stopped by the user.

- _Min distance._ In meters. Minimum distance between two locations.

- _Name template._ The name the app will use when saving the locations.

[icon="images/icons/info.jpg"]
[TIP]
_How does the background service work?_ Assuming the user sets 5 minutes and 50
meters in the settings above, the app will start by recording a location at the current
location, followed by another one at every 5 minutes *or* every time one moves 50 m
from previous location.
If subsequent locations are within a radius of 50 meters from the previous one,
a new location is not saved. If the user is not moving, only one location is saved,
but if the user is moving, a trace of the route is obtained by saving a
location every 50 meters.

===== Other

- _Mailing List._ The mail box for _Subsurface_. Users can send an email to the
Subsurface mailing list.

- _Subsurface website._ A link to the URL of Subsurface web

- _Version._ Displays the current version of the Companion App.

===== Search

Search the saved dive locations by name or by date and time.

===== Start service

Initiates the _background service_ following the previously defined settings.

===== Disconnect

This is a badly named option that disconnects the app from the server by
resetting the user ID in the app, showing the first screen where an account
can be created, retrieve the ID for an existing account or use the users own
ID. The disconnect option
is useful if a user's Android device was used to download the dive locations
of another registered diver.

===== Send all locations

This option sends all locations stored in the Android device to the server.

[[S_iphone]]
==== Using the Subsurface companion app on an _iPhone_ to record dive locations

The iPhone interface is quite simple. One needs to type the user ID (obtained
during registration) into the space reserved for it, then select "Dive in"
(see left part of the image below) and start collecting dive location information.

image::images/iphone.jpg["FIGURE: Using iPhone companion application",align="center",width=640]

Dives can be added automatically or manually. In manual mode, a dive location or waypoint is added to the GPS input stream. In automatic mode, a continuous path of GPS locations is created from which, much later, after import, subsurface can select the appropriate GPS locations based on the times of dives. The default mode for the _iphone_ is automatic. When one adds a dive, the
location service is started automatically and a red bar appears at the bottom
of the screen. After the dive one can click on the red
bar to end the location service. While the location
service is running one can only add dives using the manual mechanism.

One can edit the site name afterwards by selecting the dive
from the dive list and clicking on the site name. There are no other
editable fields. The dive list is automatically uploaded from the iPhone
to the webservice and there is not an option to
trigger upload manually.


==== Downloading dive locations to the _Subsurface_ divelog

Download dive(s) from a dive computer or enter them manually into
_Subsurface_ before obtaining the GPS coordinates from the server. The download
dialog can be reached via _Ctrl+G_ or from the _Subsurface_ Main Menu _Import
-> Import GPS data from Subsurface Service_, resulting in the image on the
left (*A*), below. On first use the DIVERID text box is blank. Provide a
DIVERID, then select the _Download_ button to initiate the download process, after
which the screen on the right (*B*) below appears:

image::images/DownloadGPS.jpg["FIGURE: Downloading Companion app GPS data",align="center"]

Note that the _Apply_ button is now active. By clicking on it, users can update the locations
of the newly entered or uploaded dives in _Subsurface_ which applies the
coordinates and names entered on the app for all the new dives that match the
date-times of the uploaded GPS localities. If one has entered the name of the dive
location in _Subsurface_ before downloading the GPS coordinates, this name will take
precedence over downloaded one.

Since _Subsurface_ matches GPS locations from the Android device and dive information from the
dive computer based on date-time data, automatic assignment of GPS data to dives is dependent
on agreement of the date-time information between these two devices. Although _Subsurface_ has
a wide range tolerance, it may be unable to identify the appropriate dive if there is
a large difference between the time in the dive computer and that of the Android device,
resulting in no updates.

Similar date-times may not always be possible and there may be many reasons for this (e.g. time zones), or
_Subsurface_ may be unable to decide which is the correct position for a dive (e.g. on repetitive
dives while running _background service_ there may be several locations that would be
included in the time range that fit not only the first dive, but one or more subsequent dives as well).
A workaround for this situation to manually edit the date-time of a dive in the _Subsurface_
Dive List *before* downloading the GPS data and then to change the date-time back again *after*
downloading GPS data.

[icon="images/icons/info.jpg"]
[NOTE]
TIPS:

- _Background service_, being a very powerful tool, may fill the location list with
  many unnecessary locations not corresponding to the exact dive point but reflecting the boat's route.
  Currently these locations are difficult to delete from the server. In some situations it
  is therefore prudent to clean up the list on the Android device before sending the dive points to the web
  server by simply deleting the inappropriate locations. This might be necessary, for
  instance, if one wants to keep the location list clear to see dives in the web service map display (see above).

- It may also make sense to give informative names to the locations sent to the web server, or at least
  to use an informative name in the _Name Template_ setting while running the _background service_,
  especially on a dive trip with many dives and dive locations.

[[S_LoadImage]]
=== Adding photographs to dives

Many (if not most) divers take a camera with them and take photographs
during a dive. One would like to associate each photograph with a specific
dive. _Subsurface_ allows one to load photos into a dive. Photos are superimposed
on the dive profile, from where they can be viewed.

==== Loading photos and getting synchronisation between dive computer and camera

Left-lick on a dive or on a group of dives on the dive list. Then right-click on this
dive or group of dives and choose the option _Load Images_:

image::images/LoadImage1_f20.jpg["FIGURE: Load images option",align="center"]

The system file browser appears. Select the folder and photographs that need
to be loaded into _Subsurface_ and click the _Open_ button.

image::images/LoadImage2_f20.jpg["FIGURE: Load images option",align="center"]

This brings up the time synchronisation dialog, shown below. The
critical problem is that the time
synchronisation is not perfect between the dive computer used during a dive,
and the camera used during that same dive. These two devices
often differ by several minutes. If _Subsurface_ can achieve synchronisation,
then the exact times of photographs can be used to position photographs on
the dive profile.

_Subsurface_ achieves this synchronisation in three ways:

- *Pro-actively*: Before the dive, ensure synchronisation of the dive computer time settings with
  the time settings of the camera by changing the date-time settings on one or both of these devices.
- *Manually*: If the user wrote down the exact camera time at the start of a dive, the
  difference in time between the two devices can be determined. Actually, as long as the device
  settings for time has not been changed in either device, one could write down the times of
  both devices after the dive or even at the end of the day. One can then manually set the time
  difference in the _Time shift_ dialog. Towards the top of the dialog is a time setting tool
  immediately under the heading _Shift times of image(s) by_, evident in figure *A* below.
  If the camera time is 7 minutes later than that of the dive computer, set the time setting
  tool to a value of 00:07.  Select either the _earlier_ or _later_ radio button.
  In the above example, the _earlier_ option is appropriate, since the photos need to be shifted
  7 minutes earlier (camera is 7 minutes ahead of dive computer). Ignore any "AM" or "PM" suffix
  in that tool. Click the _OK_ button and synchronisation is achieved.

image::images/LoadImage3b_f20.jpg["FIGURE: Synchronisation dialog",align="center"]


- *By photograph*: There is a very slick way of achieving synchronisation. If one takes a
  photograph of the face of the dive computer showing the time, then _Subsurface_ can obtain
  the exact time the photograph was taken, using the metadata that the camera stores within
  each photo. In order to do this, use the bottom half of the _Time shift_ dialog. If one uses
  the bottom part, the top part of the dialog is ignored. Click on
  the horizontal bar entitled "_Select image of dive computer showing time_. This brings up
  a file browser with which one can select the photograph of the dive computer time. Select the
  photograph using the file browser and click on _OK_. This photograph of the dive computer
  appears in the bottom panel of the _Shift times_ dialog. Now _Subsurface_ knows exactly
  when the photograph has been taken. Now set the date-time dialog to the left of the photo
  so that this tool reflects the date and time of the dive computer in the photo. When the
  date-time tool has been set, _Subsurface_ knows exactly what the time difference between
  camera and dive computer is, and synchronisation is achieved.
  Image *B* above shows a photograph of the face of the dive computer and with the date-time tool set to the
  date-time.

If the timestamp of a photograph is more than 30 minutes before or after the dive, it is not placed on
the dive profile.

==== Viewing the photos

After the images have been loaded, they appear in two places:

 - the _Photos_ tab of the *Notes* panel.
 - as tiny icons (stubs) on the dive profile at the appropriate positions reflecting the time
   each photograph was taken.
   In order to view the photos on the dive profile, activate the _show-photos_ button in the tool bar
   to the left of the dive profile:

image::images/icons/ShowPhotos_f20.png["FIGURE:Show photos toolbar button",align="left"]

This results in a profile display as in the image below:

image::images/LoadImage4_f20.jpg["FIGURE: Photos on dive profile",align="center"]

If one hovers with the mouse over any of the photo icons, then a thumbnail photo
is shown of the appropriate photo. See the image below:

image::images/LoadImage5_f20.jpg["FIGURE:Thumbnail photo on dive profile",align="center"]

Clicking on the thumbnail brings up a full size
photo overlaid on the _Subsurface_ window. This allows good viewing of
the photographs that have been added (see the image below). Note that the thumbnail
has a small dustbin icon in the bottom right hand corner (see image above). If one selects
the dustbin, the image is removed from the dive. Therefore some care
is required when clicking on a thumbnail. Images
can also be deleted using the _Photos_ tab (see text below).

image::images/LoadImage6_f20.jpg["FIGURE: Full-screen photo on dive profile",align="center"]

==== The _Photos_ tab

Photographs associated with a dive are shown as thumbnails in the _Photos_ tab of the _Notes_
panel. Photos taken in rapid succession during a dive (therefore sometimes with large
overlap on the dive profile) can easily be accessed in the _Photos_ tab. This tab serves as
a tool for individually accessing the photos of a dive, while the stubs on the dive profile
give an indication of when during a dive a photo was taken. By single-clicking on a thumbnail in
the _Photos_ panel, a photo is selected. By double-clicking a thumbnail, the full-sized image is
shown, overlaying the _Subsurface_ window. A photo can be deleted from the _Photos_ panel by selecting
it (single-click) and then by pressing the _Del_ key on the keyboard. This removes the photo both
from the _Photos_ tab as well as the dive profile.

==== Photos on an external hard disk

Most underwater photographers store their photos on an external drive. If such a drive can be mapped by the operating system
(almost always the case) the photos can be directly accessed by _Subsurface_. This facilitates the interaction
between _Subsurface_ and an external repository of photos. When associating a dive profile with photos from an
external drive, the normal procedure of selection and synchronisation (see text above) is used.
However, after the external drive has been disconnected, _Subsurface_ cannot access these photos any more.
If the display of photos is activated (using the toolbox to the left of the _Dive Profile_), the
program only shows a small white dot where each photo should be on the dive profile.
In addition the _Photos_ tab only shows the file names of the photos. This is normal behaviour.
If, later, the external drive with the photos is connected again, the photos can be seen in the normal way.

[[S_FindMovedImages]]
==== Moving photographs among directories, hard disks or computers

After a photograph has been loaded into _Subsurface_ and associated with a specific dive, the directory
 where the photo lies is stored, allowing _Subsurface_ to find the photograph when the dive is
 opened again. If the photo or the whole photo collection is moved to another drive or to a different
 machine, it is unlikely that the directory structure will remain identical to that of the original uploaded
 photo. When this happens, _Subsurface_ looks for the photos at their original location before they were moved,
 cannot find them and therefore cannot display them. Because, after moving photos, large numbers of photos
 may need to be deleted and re-imported from the new location, _Subsurface_ has a mechanism that eases the
 process of updating the directory information for each photo: automatic updates using fingerprints.

When a photo is loaded into _Subsurface_, a fingerprint for the image is calculated and stored with the
 other reference information for that photo. After moving a photo collection (that has already been loaded
 into _Subsurface_) to a different directory, disk or computer, _Subsurface_ can  perform the
 following steps:

- look through a particular directory (and all its subdirectories recursively) where photos have been moved
 to,

- calculate fingerprints for all photos in this directory, and

- if there is a match between a calculated fingerprint and the one originally calculated when a photo was
 loaded into _Subsurface_ (even if the original file name has changed), to automatically update the
 directory information so that _Subsurface_ can find the photo in the new moved directory.

This is achieved by selecting from the Main Menu: _File ->      Find moved images_. This brings up a window within
 which the NEW directory of the photos needs to be specified. Select the appropriate directory and click
 the _Scan_ button towards the bottom right of the panel. The process may require several minutes to
 complete, after which _Subsurface_ will show the appropriate photographs when a particular dive is opened.


[[Image_fingerprint_upgrade]]
****
*Upgrading existing photo collections without fingerprints*
[icon="images/icons/important.png"]
[IMPORTANT]

_Subsurface_ automatically calculates fingerprints for all images that can be accessed by _Subsurface_.
When manipulating images, ensure that all the images associated with the dive log can be accessed by _Subsurface_.

_Subsurface_ automatically checks and, if necessary, updates the fingerprints associated with a single dive if:
- The images associated with that dive are visible as thumbnails on the *Dive Profile*.
- One edits anything in the *Notes tab* panel and save the edits by selecting _Apply changes_.

****


=== Logging special types of dives

[[S_MulticylinderDives]]
==== Multicylinder dives

_Subsurface_ easily handles dives involving more than one cylinder. Multi-cylinder diving usually happens
(a) if a diver does not have enough gas for the complete dive in a single cylinder; (b) if the diver
needs more than one gas mixture because of the depth or the decompression needs of the dive. For this reason
multi-cylinder dives are often used by technical divers who dive deep or long. As far
as _Subsurface_ is concerned, there are only two types of information that need to be provided:

- *Describe the cylinders used during the dive* This is performed in the *Equipment tab* of
  the *Info* panel, as xref:cylinder_definitions[described above]. Enter the cylinders one by one,
  specifying the characteristics of the cylinder and the gas composition within each cylinder.

- *Record the times at which switches from one cylinder to another was done:* This is information
  provided by some dive computers (provided the diver indicated these changes to the dive computer
  by pressing specific buttons). If the dive computer does not provide the information, the diver has to
  record these changes using a different method, e.g. writing it on a slate.

- *Record the cylinder changes on the dive profile*: If the latter option
  was followed, the diver needs to indicate the gas change event by right-clicking at the appropriate point
  in time on the *Dive Profile* panel and indicating the cylinder to which the change was made. After
  right-clicking, follow the context menu to "Add gas change" and select the appropriate cylinder from
  those defined during the first step, above (see image below). If the
  *tank bar* button in the toolbar has been activated, the cylinder switches are also indicated in the
  tank bar.

Having performed these tasks, _Subsurface_ indicates the appropriate use of cylinders in the dive profile.
Below is a multi-cylinder dive, starting off with EAN28, then changing cylinders to EAN50 after 26 minutes
to perform decompression.

image::images/multicylinder_dive.jpg["FIGURE: Multicylinder profile",align="center"]

==== Sidemount dives

Sidemount diving is just another form of multi-cylinder diving, often with both or all cylinders having
the same gas mixture. Although it is a popular configuration for cave divers, sidemount
diving can be performed by recreational divers who have completed the appropriate training. Sidemount
dive logging involves, exactly as with multi-cylinder dives, above, three steps:

- *During the dive, record cylinder switch events*. Since sidemount diving normally involves two
  cylinders with air or with the same gas mixture, _Subsurface_ distinguishes among these different
  cylinders. In contrast, many dive computers that allow gas switching only distinguish among different
  _gases_ used, not among different _cylinders_ used. This means that when sidemount dives are downloaded
  from these dive computers, the events of switching between cylinders with the same gas are not downloaded. This may mean
  that one may have to keep a written log of cylinder switch times using a slate, or (if the dive computer
  has this facility) marking each cylinder switch with a bookmark that can be retrieved later. Returning
  from a dive with the times of cylinder changes is the only tricky part of logging sidemount dives.
- *Within _Subsurface_ describe the cylinders used during the dive*. The diver needs to provide the
  specifications of the different cylinders, using the *Equipment* tab of the *Info Panel* (see
  image below where two 12 litre cylinder were used).
- *Indicate cylinder change events on the _Subsurface_ dive profile*. Once the dive log has been imported
  from a dive computer into _Subsurface_, the cylinder switch events need to be indicated on the dive profile.
  Cylinder changes are recorded by right-clicking at the appropriate point on the dive profile and then
  selecting _Add gas change_. A list of the appropriate cylinders is shown with the
  currently used cylinder greyed out. In the image below Tank 1 is greyed out, leaving only Tank 2
  to be selected. Select the appropriate cylinder. The cylinder change is then indicated on the dive
  profile with a cylinder symbol. If the *Tank Bar* is activated using the toolbar to the left of the
  profile, then the cylinder change is also indicated on the Tank Bar (see image below). After all
  the cylinder change events have been recorded on the dive profile, the correct cylinder pressures
  for both cylinders are shown on the dive profile, as in the image below.

image::images/sidemount1.jpg["FIGURE: Sidemount profile",align="center"]

This section gives an example of the versatility of _Subsurface_ as a dive logging tool.


[[S_sSCR_dives]]
==== Semi-closed circuit rebreather (SCR) dives

[icon="images/halcyon_RB80.jpg"]
[NOTE]
Passive semi-closed rebreathers (pSCR) comprise a technical advance in diving equipment that
recirculates the breathing gas that a diver breathes, while removing carbon dioxide from
the exhaled gas. While a small amount (typically a tenth) of the exhaled breathing gas is released into the water,
a small amount of fresh gas is released from the back gas cylinder (typically containing nitrox).
A diver, using a single cylinder of breathing gas can therefore dive for much longer periods than
using a recreational open-circuit configuration. With pSCR equipment, a very small amount of breathing
gas is released every time the breather inhales. With active SCR (aSCR) equipment, in contrast, a small amount of
breathing gas is released continuously from the back cylinder.

To log pSCR dives, no special procedures are required, just the normal steps outlined above:

- Select pSCR in the _Dive Mode_ dropdown list on the *Info* panel.

- pSCR diving often involves gas changes, requiring an additional cylinder.
  Define all the appropriate cylinders as described above
  and indicate the cylinder/gas changes as described above in the section on xref:S_MulticylinderDives[multicylinder dives].

If a pSCR _Dive Mode_ has been selected, the dive ceiling for pSCR dives is adjusted for the oxygen
drop across the mouthpiece which often requires longer decompression periods. Below is a dive profile
of a pSCR dive using EAN36 on the back cylinder and oxygen for decompression. Note that this dive lasted
over two hours.

image::images/pSCR_profile.jpg["FIGURE: pSCR profile",align="center"]



[[S_CCR_dives]]
==== Closed circuit rebreather (CCR) dives

[icon="images/APD.jpg"]
[NOTE]
Closed system rebreathers use advanced technology to recirculate
gas that has been breathed while doing two things to maintain a
breathable oxygen concentration:
a) remove carbon dioxide from the gas that has been exhaled
b) regulate the oxygen concentration to remain within safe diving limits.
The CCR interface of _Subsurface_ is currently experimental
and under active development. Subsurface currently supports Poseidon MkVI
and APD Discovery/Evolution dive computers. In contrast to a conventional recreational
dive computer, a CCR system computer does not allow the download of a log
containing multiple dives. Rather, each dive is stored independently. This
means that _Subsurface_ cannot download a dive log directly from a CCR
dive computer, but that it imports CCR dive logs in the same way that it
imports dive log data from other digital databases: one dive at a time.

===== Import a CCR dive

See the section dealing with xref:S_ImportingAlienDiveLogs[Importing dive information from other
digital sources]. From the main menu of _Subsurface_, select _Import ->  Import
log files_ to bring up the xref:Unified_import[universal import dialogue]. As
explained in that section, the bottom right
hand of the import dialogue contains a dropdown list (labled _Filter:_) of appropriate devices
that currently includes(Poseidon) MkVI or APD log viewer files (import for other
CCR equipment is under active development). Having selected the appropriate CCR format and
the directory where the original dive logs have been stored from the CCR dive
computer, one can select a particular dive log file (in the case of the MkVI
it is a file with a .txt extension). After selecting the appropriate dive log,
activate the _Open_ button at the bottom right hand of the universal import dialogue.
The selected dive is imported to the _Subsurface_ dive list.

===== Displayed information for a CCR dive

_Partial pressures of gases_: The graph of oxygen partial pressure shows the
information from the oxygen sensors of the CCR equipment. In contrast to recreational
equipment (where pO~2~ values are calculated based on gas composition and dive depth),
CCR equipment provide actual measurements of pO~2~, derived from oxygen sensors.
In this case the graph for oxygen partial pressure
should be fairly flat, reflecting the setpoint settings during the dive. The mean
pO~2~ is NOT the mean oxygen partial pressure as given by the CCR equipment, but
a value calculated by _Subsurface_ as follows:

- For TWO O~2~ sensors the mean value of the two sensors are given.

- For THREE-sensor systems (e.g. APD), the mean value is also used. However
  differences of more than 0,1 bar in the simultaneous readings of different sensors are
  treated as spurious. If one of the three sensors provides spurious data, it is ignored.

- If no sensor data are available, the pO~2~ value is assumed to be equal to the setpoint.

The mean pO~2~ of the sensors is indicated with a green line,

The oxygen setpoint values as well as the readings from the individual
oxygen sensors can be shown. The display of additional CCR information is turned on by
checking the appropriate checkboxes in the _Preferences_ panel (accessible by
selecting xref:S_CCR_options[_File ->  Preferences ->  Graph_]). This part of
the _Preferences_ panel is shown in the image below, representing two checkboxes that modify
the display of pO~2~ when the appropriate toolbar button on the Dive Profile
has been activated.

image::images/CCR_preferences_f20.jpg["FIGURE: CCR preferences panel",align="center"]

Checking any of these check boxes allows the display of additional oxygen-related
information whenever the pO~2~ toolbar button on the _Profile_ panel is activated.
The first checkbox allows the display of setpoint information. This is a red line
superimposed on the green oxygen partial pressure graph and allows a comparison of the
mean measured oxygen partial pressure and the setpoint values, as shown below.

image::images/CCR_setpoint_f20.jpg["FIGURE: CCR setpoint and po2 graph",align="center"]

The second checkbox allows the display of the data from each individual oxygen sensor
of the CCR equipment. The data for each sensor is colour-coded as follows:

- Sensor 1: grey
- Sensor 2: blue
- Sensor 3: brown

The mean oxygen pO~2~ is indicated by the green line. This allows the direct comparison
of data from each of the oxygen sensors, useful for detecting abnormally low or erratic
readings from a particular sensor.

image::images/CCR_sensor_data_f20.jpg["FIGURE: CCR sensor data graph",align="center"]

The setpoint data can be overlaid on the oxygen sensor data by activating both of the above
check boxes. Partial pressures for nitrogen (and helium, if applicable) are shown in the
usual way as for open circuit dives.

_Events_: Several events are logged, e.g. switching the mouthpiece to open circuit.
These events are indicated by yellow triangles and, if one hovers over a triangle,
a description of that event is given as the bottom line in the xref:S_InfoBox[Information Box].

_Cylinder pressures_: Some CCR dive computers like the Poseidon MkVI record the
pressures of the oxygen and diluent cylinders. The pressures of these two cylinders
are shown as green lines overlapping the depth profile. In addition, start and
end pressures for both oxygen and diluent cylinders are shown in the _Equipment Tab_.
Below is a dive profile for a CCR dive, including an overlay
of setpoint and oxygen sensor data, as well as the cylinder pressure data. In this
case there is good agreement from the readings of the two oxygen sensors.

image::images/CCR_dive_profile_f22.jpg["FIGURE: CCR dive profile",align="center"]

_Equipment-specific information_: Equipment-specific information gathered by
_Subsurface_ is shown in the xref:S_ExtraDataTab[Extra data tab]. This may include setup information
or metadata about the dive.

The deco ceiling calculated by Subsurface is not very accurate because the precise pressure of nitrogen
in the loop can usually not be determined from the dive log imported from the CCR equipment. Many CCR dive
computers, however, report an internally-calculated deco ceiling that is reported in the dive log,
reflecting a more accurate assessment. The display of this ceiling is activated
by clicking the appropriate button to the left of the dive profile:

image::images/icons/cceiling.jpg["DC ceiling icon"]

The default colour of the computer-generated deco ceiling is white. However, this can be set to red
by checking the appropriate check box after selecting _File  ->  Preferences  ->  Graph_.
Below is a dive profile indicating the dive computer-generated deco ceiling:

image::images/CCR_dive_ceilingF22.jpg["FIGURE: CCR computer-generated deco ceiling",align="center"]

More equipment-specific information for downloading CCR dive logs for
Poseidon MkVI and APD equipment can be found in xref:_appendix_b_dive_computer_specific_information_for_importing_dive_information[Appendix B].

== Obtaining more information about dives entered into the logbook

=== The *Info* tab (for individual dives)

The Info tab gives some summary information about a particular dive that
has been selected in the *Dive List*. Useful information here includes the
surface interval before the dive, the maximum and mean depths of the dive, the
gas volume consumed, the surface air consumption (SAC) and the number of oxygen
toxicity units (OTU) incurred.

[icon="images/icons/info.jpg"]
[NOTE]
Gas consumption and SAC calculations:
_Subsurface_ calculates SAC and Gas consumption taking in account gas
incompressibility, particularly at tank pressures above 200 bar, making them more accurate.
Users should refer to xref:SAC_CALCULATION[Appendix F] for more information.

[[S_ExtraDataTab]]
=== The *Extra Data* tab (usually for individual dives)

When using a dive computer, it often reports several data items that cannot easily be
presented in a standardised way because the nature of the information differs from one
dive computer to another. These data often comprise setup information, metadata about
a dive, battery levels, no fly times, or gradient factors used during the dive. When
possible, this information is presented in the *Extra Data* tab. Below is an
image showing extra data for a dive using a Poseidon rebreather.

image::images/ExtraDataTab_f20.jpg["FIGURE: Extra Data tab",align="center"]

=== The *Stats* tab (for groups of dives)

The Stats tab gives summary statistics for more than one dive, assuming that
more than one dive has been selected in the *Dive List* using the standard
Ctrl-click or Shift-click of the mouse. If only one
dive has been selected, figures pertaining to only that dive are given. This tab
shows the number of dives selected, the total amount of dive time in these
dives,
as well as the minimum, maximum and mean for the dive duration,
water temperature and surface air consumption (SAC). It also shows the depth of the
shallowest and deepest dives of those selected.

[[S_DiveProfile]]
=== The *Dive Profile*

image::images/Profile2.jpg["Typical dive profile",align="center"]

Of all the panels in _Subsurface_, the Dive Profile contains the most detailed
information about each dive. The Dive Profile has a *button bar* on the left hand side
that allows control over several display options. The functions of these
buttons are described below. The main item in the Dive
Profile is the graph of
dive depth as a function of time. In addition to the obvious information of
the depth it also shows the ascent and descent rates compared to the recommended
speed of going up or down in the water column. This information is given using
different colours:
|====================
|*Colour*|*Descent speed (m/min)*|*Ascent speed (m/min)*
|Red|> 30|> 18
|Orange|18 - 30|9 - 18
|Yellow|9 - 18|4 - 9
|Light green|1.5 - 9|1.5 - 4
|Dark green|< 1.5|< 1.5
|=====================

The profile also includes depth readings for the peaks and troughs in the graph.
Thus, users should see the depth of the deepest point and other peaks. Mean depth
is plotted as a grey line, indicating mean dive depth up to a particular moment during the dive.

[icon="images/icons/scale.jpg"]
[NOTE]
In some cases the dive profile does not fill the whole area of the *Dive Profile*
panel. Clicking the *Scale* button in the toolbar on the left of the dive profile
frequently increases the size of the dive profile to fill the area of the panel efficiently.

*Water temperature* is displayed with its own blue line with temperature values
placed adjacent to significant changes.

The dive profile can include graphs of the *partial pressures*
of O~2~, N~2~, and He during the dive (see figure above) as well as a calculated and dive computer
reported deco ceilings (only visible for deep, long, or repetitive dives).
Partial pressures of oxygen are indicated in green, those of nitrogen in black,
and those of helium in dark red. These
partial pressure graphs are shown below the profile data.

[icon="images/icons/O2.jpg"]
[NOTE]
Clicking this button allows display of the partial pressure of *oxygen* during the
dive. This is depicted below the dive depth and water temperature graphs.

[icon="images/icons/N2.jpg"]
[NOTE]
Clicking this button allows display of the partial pressure of *nitrogen* during the dive.

[icon="images/icons/He.jpg"]
[NOTE]
Clicking this button allows display of the partial pressure of *helium* during the dive.
This is only of importance to divers using Trimix, Helitrox or similar breathing gasses.

The *air consumption* graph displays the tank pressure and its change during the
dive. The air consumption takes depth into account so that even when manually
entering the start and end pressures the graph is not a straight line.
Similarly to the depth graph the slope of the tank pressure gives the user information
about the
momentary SAC rate (Surface Air Consumption) when using an air integrated dive computer.
Here the colour
coding is not relative to some absolute values but relative to the average
normalised air consumption during the dive. So areas that are red or orange
indicate
times of increased normalized air consumption while dark green reflects times
when the diver was using less gas than average.

[icon="images/icons/Heartbutton.png"]
[NOTE]
Clicking on the heart rate button will allow the display of heart rate information
during the dive if the dive computer was attached to a heart rate sensor.

It is possible to *zoom* into the profile graph. This is done either by using
the scroll wheel / scroll gesture of your mouse or trackpad. By default
_Subsurface_ always shows a profile area large enough for at least 30 minutes
and 30m
 (100ft) – this way short or shallow dives are intuitively recognizable;
something
that free divers clearly won’t care about.

image::images/MeasuringBar.png["FIGURE: Measuring Bar",align="center"]

[icon="images/icons/ruler.jpg"]
[NOTE]
Measurements of *depth or time differences* can be achieved by using the
*ruler button* on the left of the dive profile panel.
The measurement is done by dragging the red dots to the two points
on the dive profile that the user wishes to measure. Information is then given
in the horizontal white area underneath the
two red dots.

[icon="images/icons/ShowPhotos.png"]
[NOTE]
Photographs that have been added to a dive can be shown on the profile
by selecting
the *Show-photo* button. The position of a photo on the profile
indicates the exact time when this photo was taken. If this button is not active,
the photos are hidden.


The profile can also include the dive computer reported *ceiling* (more
precisely, the deepest deco stop that the dive computer calculated for each
particular moment in time) as a red overlay on  the dive profile. Ascent ceilings
arise when a direct ascent to the surface increases
the risk of a diver suffering from decompression sickness (DCS) and it is necessary
to either ascend
slower or to perform decompression stop(s) before ascending to the surface. Not
all dive computers record this information and make it available for download;
for example all of the Suunto dive computers fail to make this very useful data
available to divelog software. _Subsurface_ also calculates ceilings independently,
shown as a green overlay on the dive profile.
Because of the differences in algorithms used
and amount of data available (and other factors taken into consideration at the time
of the calculation) it is unlikely that ceilings from dive computers and from _Subsurface_
are the same, even if the same algorithm and _gradient factors_ (see below) are used.
It is also quite common that _Subsurface_ calculates a ceiling for
non-decompression dives when the dive computer stayed in non-deco mode during
the whole dive (represented by the [green]#dark green# section in the profile
at the beginning of this section). This is caused by the fact that
_Subsurface’s_
calculations describe the deco obligation at each moment during a dive,
while dive computers usually take the upcoming ascent into account. During the
ascent some excess nitrogen (and possibly helium) are already breathed off so
even
though the diver technically encountered a ceiling at depth, the dive still does
not require an explicit deco stop. This feature allows dive computers to offer
longer non-stop bottom times.

[icon="images/icons/cceiling.jpg"]
[NOTE]
If the dive computer itself calculates a ceiling and makes it available to
_Subsurface_ during upload of dives, this can be
shown as a red area by checking *Dive computer reported ceiling* button on the Profile Panel.

[icon="images/icons/ceiling1.jpg"]
[NOTE]
If the *Calculated ceiling* button on the Profile Panel is clicked, then a ceiling,
calculated by _Subsurface_, is shown in green if it exists for
a particular dive (*A* in figure below). This setting can be modified in two ways:

[icon="images/icons/ceiling2.jpg"]
[NOTE]
If, in addition, the *show all tissues* button on the Profile Panel is clicked, the ceiling is shown for the tissue
compartments following the Bühlmann model (*B* in figure below).

[icon="images/icons/ceiling3.jpg"]
[NOTE]
If, in addition, the *3m increments* button on the Profile Panel is clicked, then the ceiling is indicated in 3 m increments
(*C* in figure below).

image::images/Ceilings2.jpg["Figure: Ceiling with 3m resolution",align="center"]

[icon="images/icons/ShowCylindersButton.jpg"]
[NOTE]
By selecting this icon, the different cylinders used during a dive can be represented as a coloured bar at the bottom
of the *Dive Profile*. In general oxygen is represented by a green bar, nitrogen with a yellow bar and helium with a
red bar. The image below shows a dive which first uses a trimix cylinder (red and green), followed by a switch to a nitrox cylinder
(yellow and green) after 23 minutes. Cylinders with air are shown as a light blue bar.

image::images/ShowCylinders_f20.jpg["Figure: Cylinder use graph",align="center"]


[icon="images/tissues.jpg"]

[NOTE]
Display inert gas tissue pressures relative to ambient inert gas pressure (horizontal grey line).
Tissue pressures are calculated using the Bühlmann ZH-L16 algorithm and are displayed as lines ranging from
green (faster tissues) to blue (slower tissues).
The black line, graphed above the ambient pressure, is the maximum allowable tissue supersaturation (pressure limit) derived
from the gradient factors specified in the *Preferences*. For
divers involved in planned decompression diving, efficient rates of offgasing are obtained with tissue pressures
between the ambient inert gas pressure (grey line) and the pressure limit (black line). This display is a representation
of the tissue pressures during the whole dive. In contrast, the xref:S_gas_pressure_graph[Gas Pressure Graph] in the *Information Box* on the *Dive Profile*
is an instantaneous reflection of tissue pressures at the moment in time reflected by the position of the cursor on the dive profile.

image::images/tissuesGraph.jpg["Figure: Inert gas tissue pressure graph",align="center"]

Gradient Factor settings strongly affect the calculated ceilings and their depths.
For more information about Gradient factors, see the section on xref:S_GradientFactors[Gradient Factor Preference settings]. The
currently used gradient factors (e.g. GF 35/75) are shown above the depth profile if the appropriate toolbar buttons are activated.
*N.B.:* The indicated gradient factors are NOT the gradient factors in use by the dive computer,
but those used by _Subsurface_ to calculate deco obligations
during the dive. For more information external to this manual see:

 ** http://www.tek-dive.com/portal/upload/M-Values.pdf[Understanding M-values by Erik Baker, _Immersed_ Vol. 3, No. 3.]

 ** link:http://www.rebreatherworld.com/general-and-new-to-rebreather-articles/5037-gradient-factors-for-dummies.html[Gradient factors for dummies, by Kevin Watts]


=== The Dive Profile context menu

The context menu for the Dive Profile is accessed by right-clicking while the
mouse cursor is over the Dive Profile panel. The menu allows the creation of
Bookmarks or Gas Change Event markers or manual CCR set-point changes other than the ones that might have been
imported from a Dive Computer. Markers are placed against the depth profile line
and with the time of the event set by where the mouse cursor was when the right
mouse button was initially clicked to bring up the menu. Gas Change events
involve a selection of which gas is being switched to, the list of choices being based on
the available gases defined in the *Equipment* Tab. Set-point change
events open a dialog allowing to choose the next set-point value. As
in the planner, a set-point value of zero indicates the diver is
breathing from an open circuit system while any non-zero value
indicates the use of a closed circuit rebreather (CCR).
By right-clicking while over
an existing marker a menu appears, adding options to allow deletion of the
marker or to allow all markers of that type to be hidden. Hidden events can be
restored to view by selecting Unhide all events from the context menu.

[[S_InfoBox]]
=== The *Information Box*

The Information box displays a large range of information pertaining to the dive
profile. Normally the Information Box is located to the top left of the *Dive
Profile* panel. If the mouse points outside of the *Dive Profile* panel, then
only the top line of the Information Box is visible (see left-hand part of
figure (*A*) below). The Information Box can be moved around in the *Dive Profile*
panel by click-dragging it with the mouse so that it is not obstructing
important detail. The position of the Information Box is saved and used again
during subsequent dive analyses.

image::images/InfoBox2.jpg["Figure: Information Box",align="center"]

The moment the mouse points inside the *Dive Profile* panel, the information box  expands and
shows many data items. In this situation, the data reflect the time point along
the dive profile indicated by the mouse cursor (see right-hand part of figure (*B*) above
where the Information Box reflects the situation at the position of the cursor
[arrow] in that image). Therefore, moving the cursor in the horizontal
direction allows the Information Box to show information for any point along the
dive profile.
In this mode, the Information Box gives extensive statistics about depth, gas
and ceiling characteristics of the particular dive. These include: Time period
into the dive (indicated by a @), depth, cylinder pressure (P), temperature,
ascent/descent rate, surface air consumption (SAC), oxygen partial pressure,
maximum operating depth, equivalent air depth (EAD), equivalent narcotic depth
(END), equivalent air density depth (EADD), decompression requirements at that
instant in time (Deco), time to surface (TTS), the calculated ceiling, as well
as the calculated ceiling for several Bühlmann tissue compartments.

The user has control over the display of several statistics, represented as four
buttons on the left of the profile panel. These are:

[icon="images/icons/MOD.jpg"]
[NOTE]
Clicking this button causes the Information Box to display the *Maximum Operating Depth
(MOD)* of the dive, given the
gas mixture used. MOD is dependent on the oxygen concentration in the breathing gas.
For air (21% oxygen) it is around 57 m if a maximum pO~2~ of 1.4 is specified in the *Preferences* section
(select _File_ -> Preferences -> Graph_ and edit the text box _Max pO~2~ when showing MOD_.
Below the MOD there is a markedly increased
risk of exposure to the dangers associated with oxygen toxicity.

[icon="images/icons/NDL.jpg"]
[NOTE]
Clicking this button causes the Information Box to display the *No-deco Limit (NDL)* or the
*Total Time to Surface (TTS)*. NDL is the time duration that a diver can continue with a
dive, given the present depth, that does not require decompression (that is, before an
ascent ceiling appears). Once one has exceeded the NDL and decompression is required (that
is, there is an ascent ceiling above the diver, then TTS gives the number of minutes
required before the diver can surface. TTS includes ascent time as well as decompression
time.

[icon="images/icons/SAC.jpg"]
[NOTE]
Clicking this button causes the Information Box to display the *Surface Air Consumption (SAC)*.
SAC is an indication of the surface-normalised respiration rate of a diver. The value of SAC
is less than the real
respiration rate because a diver at 10m uses breathing gas at a rate roughly double that of
the equivalent rate at the surface. SAC gives an indication of breathing gas consumption rate
independent of the depth of the dive so that the respiratory rates of different dives
can be compared. The units for SAC is litres/min or cub ft/min.

[icon="images/icons/EAD.jpg"]
[NOTE]
Clicking this button displays the *Equivalent Air Depth (EAD)* for
nitrox dives as well as the *Equivalent
Narcotic Depth (END)* for trimix dives. These are numbers of
importance to divers who use breathing gases other than air. Their
values are dependent on the composition of the breathing gas.  The EAD
is the depth of a hypothetical air dive that has the same partial
pressure of nitrogen as the current depth of the nitrox dive at
hand. A nitrox dive leads to the same decompression obligation as an
air dive to the depth equalling the EAD. The END is the depth of a
hypothetical air dive that has the same sum of partial pressures of
the narcotic gases nitrogen and oxygen as the current trimix dive. A
trimix diver can expect the same narcotic effect as a diver breathing
air diving at a depth equalling the END.

Figure (*B*) above shows an information box with a nearly complete set of data.

[[S_gas_pressure_graph]]
==== The Gas Pressure Bar Graph

On the left of the *Information Box* is a vertical bar graph indicating the
pressures of the nitrogen (and other inert gases, e.g. helium, if applicable) that the diver
was inhaling _at a particular instant during the dive_, indicated by the position
of the cursor on the *Dive Profile*. The drawing on the left below indicates the
meaning of the different parts of the Gas Pressure Bar Graph.

image::images/GasPressureBarGraph.jpg["FIGURE:Gas Pressure bar Graph",align="center"]

- The light green area indicates the total gas, with the top margin of the light green
  area indicating the total gas pressure inhaled by the diver and measured from the bottom
  of the graph to the top of the light green area. This pressure has a _relative_ value in the graph
  and does not indicate absolute pressure.

- The horizontal black line underneath the light green margin indicates the equilibrium pressure
  of the inert gases inhaled by the diver, usually nitrogen. In
  the case of trimix, it is the pressures of nitrogen and helium combined. In this example,
  the user is diving with EAN32, so the inert gas pressure is 68% of the distance from the
  bottom of the graph to the total gas pressure value.

- The dark green area at the bottom of the graph represents the pressures of inert gas in each
  of the 16 tissue compartments, following the Bühlmann algorithm, the fast tissues being on the
  left hand side.

- The top black horizontal line indicates the gradient factor that applies to the depth of
  the diver at the particular point on the *Dive Profile*. The gradient factor shown is an
  interpolation between the GFLow and GFHigh values specified in the Graph tab of the *Preferences
  Panel* of *Subsurface*.

- The bottom margin of the red area in the graph indicates the Bühlman-derived M-value, that is the
  pressure value of inert gases at which bubble formation is expected to be severe, resulting
  in decompression sickness.

These five values are indicated on the left in the graph above. The way the Gas Pressure Bar Graph changes
during a dive is indicated on the right hand side of the above figure for a diver using EAN32.

- Graph *A* indicates the situation at the start of a dive with diver at the surface. The pressures in all
  the tissue compartments are still at the equilibrium pressure because no diving has taken place.

- Graph *B* indicates the situation after a descent to 30 meters. Few of the tissue compartments have had
  time to respond to the descent, their gas pressures being far below the equilibrium gas pressure.

- Graph *C* represents the pressures after 30 minutes at 30 m. The fast compartments have attained
  equilibrium (i.e. they have reached the hight of the black line indicating the equilibrium pressure). The
  slower compartments (towards the right) have not reached equilibrium and are in the process of slowly
  increasing in pressure.

- Graph *D* shows the pressures after ascent to a depth of 4.5 meters. Since, during ascent, the total
  inhaled gas pressure has decreased strongly from 4 bar to 1.45 bar, the pressures in the different tissue
  compartments now exceed that of the total gas pressure and approaches the gradient factor value (i.e.
  the top black horizontal line). Further ascent will result in exceeding the gradient
  factor value (GFHigh), endangering the diver.

- Graph *E* indicates the situation after remaining at 4.5 meters for 10 minutes. The fast compartments
  have decreased in pressure. As expected, the pressures in the slow compartments have not changed much.
  The pressures in the fast compartments do not approach the GFHigh value any more and the diver is safer
  than in the situation indicated in graph *D*.



== Organising the logbook (Manipulating groups of dives)

=== The Dive List context menu

Several actions on either a single dive or a group of dives can be performed using the Dive List
Context Menu, found by selecting either a single dive or a group of dives and then right-clicking.

// TODO: NEEDS REPLACEMENT
image::images/ContextMenu.jpg["Figure: Context Menu",align="center"]

The context menu is used in many manipulations described below.

==== Customising the columns showed in the *Dive List* panel

image::images/DiveListOptions.jpg["Example: Dive list info options",align="center"]

The default information in the *Dive List* includes, for each dive, Dive_number, Date, Rating, Dive_depth,
Dive_duration and Dive_location. This information can be controlled and changed by right-clicking on the
header bar of the *Dive List*. For instance, a right-click on the 'Date' header brings up a list of items
that can be shown in the dive list (see above). Select an item to be shown in the *Dive List* or to be
deleted from the dive list (reflected by the check symbols) and the list is immediately updated. Preferences for information
shown in the *Dive List* are saved and used when _Subsurface_ is re-opened.

[[S_Renumber]]
=== Renumbering the dives

Dives are normally numbered incrementally from non-recent dives (low sequence
numbers) to recent dives (having the highest sequence numbers). The numbering
of the dives is not always consistent. For instance, when non-recent dives are
added to the dive list the numbering does not automatically follow on because
of the dives that are more recent in date/time than the newly-added dive with
an older date/time. Therefore, one may sometimes need to renumber the dives.
This is performed by selecting (from the Main Menu) _Log ->  Renumber_. Users are
given a choice with respect to the lowest sequence number to be used.
Completing this operation results in new sequence numbers (based on date/time)
for the dives in the *Dive List* panel.

One can also renumber a few selected dives in the dive list. Select the dives that
need renumbering. Right-click on the selected list and use the Dive List Context Menu
to perform the renumbering. A popup window appears requiring the user to specify
the starting number for the renumbering process.

[[S_Group]]
=== Grouping dives into trips and manipulating trips

For regular divers, the dive list can rapidly become very long. _Subsurface_
can group dives into _trips_. It performs this by grouping dives that have
date/times not separated in time by more than two days, thus creating
a single heading for each diving trip represented in the dive log. Below is an
ungrouped dive list (*A*, on the left) as well as the corresponding grouped dive
list comprising five dive trips (*B*, on the right):

image::images/Group2.jpg["Figure: Grouping dives",align="center"]

Grouping into trips allows a rapid way of accessing individual dives without
having to scan a long lists of dives. In order to group the dives in a dive list,
(from the Main Menu) select _Log ->  Autogroup_. The *Dive List* panel
now shows only the titles for the trips.

==== Editing the title and associated information for a particular trip

Normally, in the dive list, minimal information is included in the trip title.
More information about a trip can be added by selecting its trip title from
the *Dive List*. This shows a *Trip Notes* tab in the *Notes* panel. Here
one can add or edit information about the date/time, the trip location and any
other general comments about the trip as a whole (e.g. the dive company that was
dived with, the general weather and surface conditions during the trip, etc.).
After entering this
information, select *Save* from the buttons at the top right
of the *Trip Notes*
tab. The trip title in the *Dive List* panel should now reflect the
edited information.

==== Viewing the dives during a particular trip

Once the dives have been grouped into trips, users can expand one or more
trips by clicking the arrow-head on the left of each trip title. This expands
the selected trip, revealing the individual dives performed during the trip.

==== Collapsing or expanding dive information for different trips

After selecting a particular trip in the dive list, the
context menu allows several possibilities to expand or collapse dives
within trips. This includes expanding all trips and collapsing all trips.

==== Merging dives from more than one trip into a single trip

After selecting a trip title, the context menu allows the merging
of trips by either merging the selected trip with the trip below or with the
trip above. (Merge trip with trip below; Merge trip with trip above)

==== Splitting a single trip into more than one trip

If a trip includes ten dives, the user can split this trip into two trips (trip 1:
top 4 dives; trip 2: bottom 6 dives) by selecting and right-clicking the top
four dives. The resulting context menu allows the user to create a new trip by
choosing the option *Create new trip above*. The top four dives are then
grouped
into a separate trip. The figures below shows the selection and context menu
on the left (A) and
the completed action on the right (B):

image::images/SplitDive3a.jpg["FIGURE: Split a trip into 2 trips",align="center"]

=== Manipulating single dives

==== Delete a dive from the dive log

Dives can be permanently deleted from the dive log by selecting and
right-clicking them to bring up the context menu, and then selecting *Delete
dive(s)*. Typically this would apply to a case where a user wishes to delete
workshop
calibration dives of the dive computer or dives of extremely short duration.

==== Unlink a dive from a trip

Users can unlink dives from the trip to which they belong. In order to do this,
select and right-click
the relevant dives to bring up the context menu. Then select the option *Remove dive(s)
from trip*. The dive(s) now appear immediately above or below the trip to
which they belonged, depending on the date and time of the unlinked dive.

==== Add a dive to the trip immediately above

Selected dives can be moved from the trip to which they belong and placed within
a separate trip. To do this, select and right-click
the dive(s) to bring up the context menu, and then select *Create new trip above*.

==== Shift the start time of dive(s)

Sometimes it is necessary to adjust the start time of a dive. This may apply to
situations where dives are performed in different time zones or when the dive
computer has an erroneous time. In order to do this, select and right-click
the dive(s) to be
adjusted. This action brings up the context menu on which the *Shift times*
option should be selected. User must then specify the
time
(in hours and minutes) by which the dives should be adjusted and click on the
option indicating whether the time adjustment should be ealier or later.

==== Merge dives into a single dive

Sometimes a dive is briefly interrupted, e.g. if a diver returns to the surface
for a few minutes, resulting in two or more dives being recorded by the dive
computer and appearing as different dives in the *Dive List* panel. Users can
merge these dives onto a single dive by selecting the appropriate dives,
right-clicking them to bring up the context menu and then selecting *Merge selected
dives*. It may be necessary to edit the dive information in the *Notes*
panel to reflect events or conditions that apply to the merged dive. The figure
below shows the depth profile of two dives that were merged:

image::images/MergedDive.png["Example: Merged dive",align="center"]

==== Undo dive manipulations

Important actions on dives or trips, described above, can be undone or redone.
This includes: _delete dives_, _merge dives_, _renumber dives_ and _shift dive times_.
To do this after performing any of these actions, from the *Main Menu* select
_Edit_. This brings up the possibility to _Undo_ or _Redo_ an action.


[[S_Filter]]
=== Filtering the dive list

The dives in the *Dive List* panel can be filtered, that is, one can select only some
of the dives based on their attributes, e.g. dive tags, dive site, dive master, buddy or protective
clothing. For instance, filtering allows one to list the deep dives at a particular
dive site, or otherwise the cave dives with a particular buddy.

To open the filter, select _Log ->  Filter divelist_ from the main menu. This opens the
_Filter Panel_ at the top of the _Subsurface_ window. Three icons are located at the top
right hand of the filter panel (see image below). The _Filter Panel_ can be reset
(i.e. all current filters cleared) by selecting the *yellow angled arrow*. The _Filter Panel_ may also be
minimised by selecting the *green up-arrow". When minimised, only these three icons are shown.
The panel can be maximised by clicking the icon that minimised the panel. The filter may also be
reset and closed by selecting the *red button* with the white cross.

image::images/Filterpanel.jpg["Figure: Filter panel",align="center"]

Four filter criteria may be used to filter the dive list: dive tags, person (buddy / dive master), dive site
and dive suit, each of which is represented by a check list with check boxes. Above
each check list is a second-level filter tool, allowing the listing of only some of
the attributes within that check list. For instance, typing "_ca_" in the filter
textbox above the tags check list results in the tags check list being reduced
to "_cave_" and "_cavern_". Filtering of the check list enables the rapid finding
of search terms for filtering the dive list.

To activate filtering of the dive list, check at least one check box in one of
the four check lists. The dive list is then shortened to include
only the dives that pertain to the criteria specified in the check lists.
The four check lists work as a filter with _AND_ operators, Subsurface
filters therefore  for _cave_ as a tag AND _Joe Smith_ as a buddy; but the
filters within a category are inclusive - filtering for _cave_ and _boat_
shows those dives that have either one OR both of these tags.

[[S_ExportLog]]
== Exporting the dive log or parts of the dive log

There are two routes for the export of dive information from Subsurface:

- Export dive information to _Facebook_

- xref:S_Export_other[Export dive information to other destinations or formats]

[[S_facebook]]
=== Exporting dive information to _Facebook_

Export of dives to _Facebook_ is handled differently from other types of export because
a connection to _Facebook_ is required, needing a _Facebook_ userID and password.
If, from the *Main Menu*, one selects _File ->  Preferences ->  Facebook_, a login screen is presented
(image *A* to the left, below).  Provide a _Facebook_ userID and password.
Once a successful login to _Facebook_ has been achieved, the panel
in image *B*, below is presented, including a _Disconnect from Facebook_ button to close the
_Facebook_ connection.

image::images/facebook1_f20.jpg["Figure: Facebook login",align="center"]

From the _Subsurface_ window it is easy to determine whether _Subsurface_ has a valid connection to _Facebook_
From the *Main Menu*, select _Share on -> Facebook_ (image *A*, below). Normally, the _Facebook_ option is greyed out. But
if there is a connection to _Facebook_, this option is active (i.e. in black colour and can be selected).

Having established a login to _Facebook_, transfer of a dive profile to one's _Facebook_ timeline is easy.
Ensure that the dive to be transfered to the timeline is depicted in the _Subsurface_ *Dive Profile* panel. If, from the *Main Menu*, one selects _Share on -> Facebook_ (see image *A* below), a dialogue is shown, determining the amount of additional information transferred
with the dive profile (image *B*, below). In order to transfer a dive profile to _Facebook_, the name of a
_Facebook_ album needs to be provided. The checkboxes on the lefthand side allow one to determine how much
additional information should be transferred with the dive profile. This information is shown in the text box
on the right hand side of the panel (image *B*, below). One can easily edit the message that will be posted
with the dive profile. Having specified the additional information and verified the text, select
the _OK_ button that triggers the transfer to _Facebook_. After a while, an acknowledgement dialogue appears,
indicating successful transfer to _Facebook_.

Both the album created and the post to one's timeline will be marked as
private. In order for friends to be able to see the post,
change its permissions from a regular Facebook login either in a browser
or a Facebook app. While this is an extra step
this is the better solution to avoid having unwanted posts in one's public
timeline.

image::images/facebook2_f20.jpg["Figure: Facebook login",align="center"]

If required, then close the _Facebook_ connection by either closing _Subsurface_ or by selecting _File ->  Preferences ->  Facebook_ from
the Main Menu, and clicking the appropriate button on the Facebook Preferences panel.

[[S_Export_other]]
=== Export dive information  to other destinations or formats
For non-_Facebook exports_, the export function can be reached by selecting _File ->  Export_, which brings up
the Export dialog. This dialog always gives two options: save ALL dives, or save only
the dives selected in *Dive List* panel of _Subsurface_. Click the appropriate
radio button (see images below).

image::images/Export_f20.jpg["Figure: Export dialog",align="center"]

A dive log or part of it can be saved in three formats:

* _Subsurface XML_ format. This is the native format used by _Subsurface_.

* Universal Dive Data Format (_UDDF_). Refer to _http://uddf.org_ for more information.
  UDDF is a generic format that enables communication among many dive computers
  and computer programs.

* _Divelogs.de_, an Internet-based dive log repository. In order to upload to _Divelogs.de_,
  one needs a user-ID as well as a password for _Divelogs.de_. Log into _http://en.divelogs.de_
  and subscribe to this service in order to upload dive log data from _Subsurface_.

* _DiveShare_ is also a dive log repository on the Internet focusing on the recreational
  dives. In order to upload dives one has to provide a used ID, so registration with
  _http://scubadiveshare.com_ is required.

* _CSV dive details_, that includes the most critical information of the dive
  profile. Included information of a dive is: dive number, date, time, buddy,
  duration, depth, temperature and pressure: in short, most of the information
  that recreational divers enter into handwritten log books.

* _CSV dive profile_, that includes a large amount of detail for each dive, including
  the depth profile, temperature and pressure information of each dive.

* _HTML_ format, in which the dive(s) are stored in HTML files, readable
  with an Internet browser. Most modern web browsers are supported, but JavaScript
  must be enabled. The HTML export cannot be changed or edited.
  It contains most of the information recorded in the dive log. However, it does not show the
  calculated values in the *Dive Profile* panel, e.g. calculated cylinder pressure, gas
  pressures and MOD. The HTML export contains a search
  option to search the dive log. HTML export is specified on the second tab of the
  Export dialog (image *B* above). A typical use of this option is to export all one's
  dives to a smartphone or a tablet where it would serve as a very portable record
  of dives useful for dive companies that wish to verify the dive history of a diver,
  often doing away with the need to carry one's original logbook with one
  when doing dives with dive companies.

* _Worldmap_ format, an HTML file with a world map upon which each dive and
  some information about it are indicated. This map is not editable. If one selects any
  of the dive sites on the map, a summary of the dive is available in text, as shown
  in the image below.

image::images/mapview_f20.jpg["Figure: HTML Map export view",align="center"]


* _Image depths_, which creates a text file that contains the file names of all
  photos or images  attached
  to any of the selected dives in the _Dive List_, together with the depth under water where
  of each of those photos were taken.

* _General Settings_, under the HTML tab, provides the following options:

** Subsurface Numbers: if this option is checked, the dive(s) are exported with the
   numbers associated with them in Subsurface, Otherwise the dive(s) will be numbered
   starting from 1.
** Export Yearly Statistics: if this option is checked, a yearly statistics table will
   be attached to the HTML exports.
** Export List only: a list of dives only (date, time, depth, duration) will be exported
   and the detailed dive information, e.g. dive profile, will not be available.

* Under _Style Options_ some style-related options are available like font
  size and theme.

Export to other formats can be achieved through third party facilities, for
instance _www.divelogs.de_.

[[S_Cloud_access]]
== Keeping a _Subsurface_ dive log in the Cloud

For each diver, dive log information is highly important. Not only is it a record
of diving activities for one's own pleasure, but it is important information required
for admission to further training courses or (sometimes) even diving sites. The
security of the dive log is therefore critical. In order to have a dive log that is
resistant to failure of a home computer hard drive, loss or theft of equipment, the
Cloud is an obvious solution. This also has the added benefit that one can access one's dive
log from anywhere in the world without having to carry it with oneself. For this
reason, facilities such as _divelogs.de_ and _Diving Log_ offer to store
dive log information on the Internet.

_Subsurface_ includes access to a transparently integrated cloud storage
back end that is available to all Subsurface users. Storing and retrieving a dive log
from the cloud is no more difficult than accessing the dives on the local hard disk.
The only requirement is that one should first register as a user on the cloud.
To use _Subsurface cloud storage_ , follow these steps:

=== Create a cloud storage account

** Open the *Network Preferences* by selecting _File_ -> _Preferences_ -> _Network_.
** In the section headed _Subsurface cloud storage_, enter an email address that
   _Subsurface_ can use for user registration.
** Enter a novel password that _Subsurface_ will use to store the
  dive log in the cloud.
** Click _Apply_ to send the above email address and password to the
  (remote) cloud server. The server responds by sending a verification PIN to
  the above email address (This is the *only* occasion that _Subsurface_ uses the
  email address provided above). The *Network Preferences* dialog now has a new PIN text
   box, not visible previously.
** Enter the PIN in the corresponding text box in the *Network Preferences* dialog
(this field is only visible while the server is waiting for email
address confirmation)
** Click _Apply_ again. The _Subsurface cloud storage_ account
will be marked as verified and the _Subsurface cloud storage_ service is initialised for use.

=== Using _Subsurface cloud storage_

** Once the cloud storage has been initialised, two new items appear in the
   _File_ menu of the main menu system: _Open cloud storage_ and _Save to cloud storage_.
These options allow the user to load and save data to the _Subsurface
cloud storage_ server.
** In the _Defaults Preferences_ tab, one can select to use the _Subsurface cloud
storage_ data as one's default data file by checking the check box marked _Cloud storage default file_.
 This means that the data from
the _Subsurface cloud storage_ is loaded when _Subsurface_ starts ans saved there when one closes _Subsurface_.

** _Subsurface_ keeps a local copy of the data and the cloud facility remains fully
functional even if used while disconnected to the Internet. _Subsurface_ simply synchronises the
data with the cloud server the next time ithe program is used while the computer is
connected to the Internet.

[[S_Cloud_storage]]
=== Web access to _Subsurface cloud storage_

One of the nice side benefits of using _Subsurface cloud storage_ is that
one can also access one's dive data from any web browser. Simply open
https://cloud.subsurface-divelog.org[_https://cloud.subsurface-divelog.org_],
log in with the same email and password, and you can see an HTML export of
the last dive data that was synced to the _Subsurface cloud storage_. The dive information
that is shown is only the contents of the recorded dive logs, NOT the calculated values
shown in the *Profile* panel,
including some cylinder pressures, deco ceilings and O~2~/He/N~2~ partial pressures.

=== Other cloud services

If one prefers not to use the integrated cloud storage of dive logs (and
don't need the web access), it is also simple to store
dive logs in the cloud using several of the existing facilities on the
Internet.
For instance
http://www.dropbox.com/[_Dropbox_]
offers a free application that allows
files on the Dropbox servers to be seen as a local folder on one's desktop computer.

image::images/Cloud.jpg["FIGURE: Dropbox folder",align="center"]

The _Dropbox_ program creates a copy of the _Dropbox_ Internet Cloud content on one's
desktop computer. When the computer is connected to the Internet, the Internet
content is automatically updated. Therefore both the _Open_ and _Save_ of dive logs are done
using the local copy of the dive log in the local _Dropbox_ folder, so there's no need
for a direct internet connection. If the local copy is modified, e.g. by adding a dive,
the remote copy in the _Dropbox_ server in the Cloud will be automatically updated whenever
Internet access is available.

In this way a dive log in
one's _Dropbox_ folder can be accessed seamlessly from the Internet and can
be accessed from any place with Internet access. Currently there are no costs
involved for this service. Dropbox (Windows, Mac
and Linux) can be installed by accessing the
http://www.dropbox.com/install[_Install Page on the Dropbox website_]
. Alternatively one can use _Dropbox_ as a mechanism to backup one's dive log. To
Store a dive log on _Dropbox_, select _File ->  Save as_ from the _Subsurface_ main menu,
navigate to the _Dropbox_ folder and select the _Save_ button. To access the dive log
in _Dropbox_, select _File ->  Open Logbook_ from the _Subsurface_
main menu and navigate to the dive log file in the _Dropbox_ folder and select the
_Open_ button.

Several paid services exist on the Internet (e.g. Google, Amazon) where the same
process could be used for the Cloud-based storage of dive logs.


[[S_PrintDivelog]]
== Printing a dive log

_Subsurface_ provides a simple and flexible interface to print a whole dive log or only a few selected dives.
  Pre-installed templates or a custom written template can be used to choose where the data are fitted into the page.

Before printing, two decisions are required:

- Should the whole dive log be printed or only part of it? If only part of the
  dive log is required, then select the required dives from the *Dive List* panel.
- If the dive profiles needs printing, what gas partial pressure information should be shown? Select
  the appropriate toggle-buttons on the button bar to the left of the *Dive Profile* panel.

If _File ->  Print_ is selected from the Main menu, the the dialogue below (image *A*) appears. Three
specifications are needed to achieve the desired information and page layout:

image::images/Print1_f22.jpg["FIGURE: Print dialogue",align="center"]

1. Under _Print type_ select one of two options:

- _Dive list print_: Print dives from the *Dive List* panel with profiles and other information.
- _Statistics print_: Print yearly statistics of the dives.

2. Under _Print options_ select:

- Printing only the dives selected from the dive list prior to
  activating the print dialogue by checking the box _Print only
  selected dives_. If this check box is *not* checked all dives in
  the *Dive List* panel are printed.
- Printing in colour, achieved by checking the box with _Print in colour_. If this check box
  is not checked, printing is in monochrome (grey scale).

3. Under _Template_ select a template to be used as the page layout. There are several templates
(see image *B*, above).

- _Table_: This prints a summary table of all dives selected (see below).

image::images/Print_summarylist_f22.jpg["FIGURE: Print summary table",align="center"]

- _Flow layout_: Print the text associated with each dive without printing the dive profiles
     of each dive (see below):

image::images/Print_flow_layout_f22.jpg["FIGURE: Print flow layout",align="center"]

- _One Dive_: Print one dive per page, also showing the dive profile (see below)

image::images/print2_f22.jpg["FIGURE: Print one dive / page",align="center"]


- _Two Dives_: Print two dives per page, also showing the dive profiles.
- _Six Dives_: Print six dives per page, also showing the dive profiles.

Users can _Preview_ the printed page by selecting the _Preview_ button on the
dialogue (see image *A* at the start of this section). After preview, changes to
the options in the print dialogue can be made, resulting in a layout that fits personal taste.

Next, select the _Print_ button (see image *A* at the start of this section). This activates the regular print
dialogue used by the user operating system,
allowing one to choose a printer and to set its properties (see image below):

image::images/Print_print_f22.jpg["FIGURE: Print dialog",align="center"]

Set the print resolution of the printer to an appropriate value by changing
the printer _Properties_. Finally, select the _Print_ button to print the dives.
Below is a (rather small) example of the output for one particular page.

image::images/Printpreview.jpg["FIGURE: Print preview page",align="center"]

=== Writing a custom print template (advanced)

Writing a custom template is an effective way to produce highly customized printouts. Subsurface uses HTML templates
to render printing. One can create a template, export a new template, import an existing template and delete an existing template by using the appropriate buttons under the _Template_ dropdown list in the print dialogue. See <<S_APPENDIX_E,APPENDIX E>> for information on how to write or modify a template.

[[S_Configure]]
== Configuring a dive computer

_Subsurface_ enables one to configure a dive computer. Currently the Heinrichs-Weikamp (OSTC 2, OSTC 3) and
Suunto Vyper (Stinger, Mosquito, D3, Vyper, Vytec,
Cobra, Gekko and Zoop) family of dive computers are supported. A large number of settings of these dive computers
can be read and changed to different values. As a first step, ensure that the appropriate hardware driver
is installed for the dive computer (also required for downloading dives) and that the device name of the dive computer is known.
See <<_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer,APPENDIX A>> for information on how to do this.

Once the dive computer is connected to the _Subsurface_ computer, select _File ->  Configure dive
computer_ from the _Main Menu_. Provide the appropriate device name in the text box at the
top of the configuration panel and select the appropriate dive
computer model from the panel on the left-hand (see image below).

image::images/Configure_dc_f20.jpg["FIGURE: Configure dive computer",align="center"]

Using the appropriate buttons on the configuration panel, the following actions can be performed:

 - *Retrieve available details*. This loads the existing configuration from the dive computer
   to _Subsurface_, showing it in the configuration panel.
 - *Save changes to device*. This changes the configuration of the
   dive computer to correspond to the information shown in the configuration panel.
 - *Backup*. This saves the configuration data to a file. _Subsurface_ asks for
   a file location and file name for the saved information.
 - *Restore backup*. This loads the information from a backup file and displays it
   in the configuration panel.
 - *Update firmware*. If new firmware is available for the dive computer, this is
   loaded into the dive computer.


[[S_Preferences]]
== Setting user _Preferences_ for _Subsurface_

There are several user-definable settings within _Subsurface_, found by selecting
_File ->  Preferences_. The settings are performed in
seven groups: *Defaults*, *Units*, *Graph*, *Language* and *Network*, *Facebook* and *Georeference*,
all of which
operate on the same principles: the user must specify the settings that are to be changed, then
these changes are saved using the *Apply* button. After applying all the new settings users can then
leave the settings panel by selecting *OK*. If *Discard* is selected, changes to the preferences
are not saved.

=== Defaults

There are several settings in the *Defaults* panel:

image::images/Pref1_f20.jpg["FIGURE: Preferences defaults page",align="center"]

  ** *Lists and tables*: Here one can specify the font type and font size of the
     *Dive Table* panel. By decreasing the font size of the *Dive Table*, users can see more dives on a screen.

  ** *Dives*: For the _Default Dive File_ one needs to specify the directory and
     file name of one's
     electronic dive log book. This is a file with filename extension of either _.xml_ or _.ssrf_. When
     launched, _Subsurface_ will automatically load the specified dive log book. There are three options:
     - _No default file_: When checked, _Subsurface_ does not automatically load a dive log at startup.
     - _Local default file_: When checked, _Subsurface_ automatically loads a dive log from the local hard disk
       as described above.
     - _Cloud storage default file_: When checked, _Subsurface automatically loads the dive log from the cloud
       device that was initialised using the *Preferences* _Network_ tab (see below).

  ** *Display invalid*:  Dives can be marked as invalid (when a user wishes to hide
     dives that he/she doesn't consider valid dives, e.g. pool dives, but still want to
     keep them in the dive log). This controls whether those dives are displayed in
     the dive list.

  ** *Default cylinder*: Specify the default cylinder listed in
     the *Equipment* tab of the *Notes* panel.

  ** *Animations*: Some actions in showing the dive profile are performed using
     animations. For instance, the axis values for depth and time change from dive to
     dive. When viewing a different dive, these changes in axis characteristics do not
     happen instantaneously, but are animated. The _Speed_ of animations can be controlled
     by setting this slider
     with faster animation speed to the left, and a 0 value representing no animation
     at all.

  ** *Clear all settings*: As indicated in the button below this heading, all settings are
     cleared and set to default values.

=== Units
image::images/Pref2_f20.jpg["FIGURE: Preferences Units page",align="center"]

Here users can choose between metric and imperial units of depth, pressure,
volume, temperature and mass. By selecting the Metric or Imperial radio button
at the top, one can specify that all units are in the chosen measurement system.
Alternatively, if one selects the *Personalise* radio button, units can be selected
independently, with some units in the metric system and others in imperial.

Irrespective
of the above settings, dive time measurements can be either in seconds or minutes.
Choose the appropriate option. GPS coordinates can be represented either as
traditional coordinates (degrees, minutes, seconds) or as decimal degrees
Choose the appropriate option.

=== Graph
[[S_CCR_options]]
image::images/Pref3_f20.jpg["FIGURE: Preferences Graph page",align="center"]

[[S_GradientFactors]]
This panel allows two type of selections:

* *Show*: Here users can specify the amount of information shown as part of
  the dive profile:
** Thresholds: _Subsurface_ can display the nitrogen, oxygen and the helium partial pressures during
   the dive, enabled by using the toolbar on the left hand side of the *Dive Profile*
   panel. For each of these graphs users can specify a threshold value on the right-hand side of the
   Preferences panel. If any of the graphs go above the specified threshold level, the graph is
   highlighted in red, indicating that the particular partial pressure threshold has been exceeded.
** _Max pO~2~ is used for calculating the MOD when displaying the maximum operative depth (MOD)
   for a dive. Specify an appropriate partial pressure. A value of 1.4 is commonly used.
** _Draw dive computer reported ceiling red_: This checkbox allows exactly what it says. By default
   the computer reported ceiling is shown in white.
   Not all dive computers report ceiling values. If the dive computer does report it, it may differ
   from the ceilings calculated by _Subsurface_ because of the different algorithms and
   gradient factors, as well as the dynamic way that a
   dive computer can calculate ceilings during a dive.
** _Show unused cylinders in Equipment Tab_: This checkbox allows display of information about unused cylinders when viewing the *Equipment Tab*. Conversely, if this box is not checked, and if any cylinders entered using the *Equipment Tab* are not used (e.g. there was no gas switch to such a cylinder), then these cylinders are omitted from that list.
**  _Show average depth_: If this box is checked, the *Dive Profile* panel contains a grey line that indicates
    the mean depth of the dive up to any time instant during the dive. Normally this is a u-shaped line indicating the deepest mean depth just before the
   ascent.

* *Misc*:

[[GradientFactors_Ref]]
** Gradient Factors (GFLow and GFHigh):* Set the _gradient factors_ used while diving. GF_Low is
   the gradient factor at depth and GF_High is used just below the surface.
   At intermediate depths gradient factors between GF_Low and GF_High are used.
   Gradient factors add conservatism to the nitrogen exposure during a dive, in a
   similar way that many dive computers have a conservatism setting. The lower
   the value of a gradient factor, the more conservative the calculations are with
   respect to nitrogen loading and the deeper the ascent ceilings are. Gradient
   factors of 20/60 are considered conservative and values of 70/90 are considered
   harsh. Checking the *GFLow at max depth* box causes GF_Low to be used at the
   deepest depth of a dive. If this box is not checked, GF_Low is applied at
   all depths deeper than the first deco stop. For more information see:

 *** http://www.tek-dive.com/portal/upload/M-Values.pdf[Understanding M-values by Erik Baker, _Immersed_ Vol. 3, No. 3.]

 *** link:http://www.rebreatherworld.com/general-and-new-to-rebreather-articles/5037-gradient-factors-for-dummies.html[Gradient factors for dummies, by Kevin Watts]

 ** _CCR: Show setpoints when viewing pO2:_ With this checkbox ativated, the pO~2~
    graph on the dive profile has an overlay in red which inticates the CCR setpoint
    values. See the section on xref:S_CCR_dives[Closed Circuit Rebreather dives].

 ** _CCR: Show individual O~2~ sensor values when viewing pO~2~:_ Show the pO~2~
    values associated with each of the individual oxygen sensors of a CCR system.
    See the section on xref:S_CCR_dives[Closed Circuit Rebreather dives].

 *  *Configuring dive planning using rebreather equipment:*

 ** _Default CCR setpoint for dive planning:_ Specify the O~2~ setpoint for a
    CCR dive plan. This determines the pO~2~  maintained
    during a particular dive. Setpoint changes during the dive can be added via the
    profile context menu.

 ** _pSCR O~2~ metabolism rate:_ For a semiclosed rebreather (pSCR) system, this is the
    volume of oxygen used by a diver during a minute. Set this value for pSCR dive planning
    and decompression calculations.

 ** _pSCR ratio:_ For pSCR equipment the dump ratio is the ratio of gas released to the
    environment to that of the gas recirculated to the diver. Set this value for a
    pSCR dive plan. A 1:10 ratio is commonly used.


=== Language
Choose a language that _Subsurface_ will use.

image::images/Pref4_f20.jpg["FIGURE: Preferences Language page",align="center"]

A checkbox allows one to use the _System Default_ language which in most cases
will be the correct setting; with this _Subsurface_ simply runs in the same
language / country settings as the underlying operating system. If this is for some reason
undesirable one can uncheck this checkbox and pick a language / country
combination from the list of included localizations. The _Filter_ text box allows
one to list similar languages. For instance there are several system variants of English
or French. *This particular preference requires a restart of _Subsurface_ to take
effect*.

=== Network
This panel facilitates communication between _Subsurface_ and data sources on the Internet.
This is important, for instance, when _Subsurface_ needs to communicate with Internet
services such as Cloud storage or the <<S_Companion,_Subsurface Companion app_>>. These Internet requirements are determined by one's type of
connection to the Internet and by the Internet Service Provider (ISP) used.
One's ISP should provide the appropriate information.

image::images/Pref5_f20.jpg["FIGURE: Preferences Network page",align="center"]

This dialogue has three sections:

** _Proxy type_:
If a proxy server is used for Internet access, the type of proxy needs to be selected from the dropdown list,
after which the IP address of the host and the appropriate port number should
be provided. If the proxy server uses authentication, the appropriate userID and
password are required so that _Subsurface_ can automatically pass
through the proxy server to access the Internet. This information is usually obtained
from one's ISP.

** _Subsurface cloud storage_: To store one's dive log in the cloud, a valid email address
   and password are required. This allows _Subsurface_ to email security information
   regarding cloud storage to a user, and to set up the cloud storage appropriately.
   Two additional options are given:
   - _Sync to cloud in the background_: This option allows saving of dive information to the cloud storage
   while the user performs other tasks within _Subsurface_.
   - _Save password locally_: This allows local storage of the cloud storage password. Note that this
   information is saved in raw text form, not encoded in any way.

** _Subsurface web service_: When one subscribes to the <<S_Companion,Subsurface web service>>, a very
     long and hard-to-remember userID is issued. This is the place to save that userID. By
     checking the option _Save User ID locally?_, one ensures that a local copy of that userID
     is saved.


[[S_Facebook]]
=== Facebook Accesss
This panel allows one to log into a Facebook account in order to transfer information
from Subsurface to Facefook.

image::images/Pref6_f20.jpg["FIGURE: Facebook login panel",align="center"]

If one provides a valid Facebook userID and password, a
connection to Facebook is created. The connection to Facebook is closed when one
closes down Subsurface. Currently the checkbox labelled "Keep me logged in to Subsurface",
on the login screen has no effect.
See the section xref:S_facebook[Exporting dive profiles to Facebook]
for more information.

=== Georeference

_Subsurface_ provides a geo-lookup service (that is, given the coordinates of a dive site (derived from
a click on the *Dive Map panel* at the bottom right of the _Subsurface_ window, or from a GPS instrument or
from the _Subsurface_ Companion app), a lookup on the Internet is performed to find
the name of the closest known location. Obviously this function only works if _Subsurface_ has an
Internet connection. The preference of the dive site name can be configured, e.g. _Country/State/City_
or _City/State/Country_ (see image below).

image::images/Pref7_f20.jpg["FIGURE: Facebook login panel",align="center"]

[[S_DivePlanner]]
== The _Subsurface_ dive planner
Dive planning is an advanced feature of _Subsurface_, accessible by selecting
_Log ->  Plan Dive_ from the main menu. It allows calculation of
nitrogen load during a dive by using the Bühlmann ZH-L16 algorithm with the addition
of gradient factors as implemented by Erik Baker.

****
[icon="images/icons/warning2.png"]
[WARNING]

The _Subsurface_ dive planner IS CURRENTLY EXPERIMENTAL
and assumes the user is already familiar with the _Subsurface_
user interface. It is explicitly used under the following conditions:

- The user is conversant with dive planning and has the necessary training to perform
  dive planning.
- The user plans dives within his/her certification limits.
- Dive planning makes large assumptions about the characteristics of the _average person_
  and cannot compensate for individual physiology or health or personal history or
  life style characteristics.
- The safety of a dive plan depends heavily on the way in which the planner is used.
- The user is familiar with the user interface of _Subsurface_.
- A user who is not absolutely sure about any of the above requirements should not use
  this feature.
****

=== The _Subsurface_ dive planner screen

Like the _Subsurface_ dive log, the planner screen is divided into several sections (see image below). The *setup*
parameters for a dive are entered into the several sections on the left hand side of the screen.
The setup is divided into several sections: Available Gases, Rates, Planning, Gas Options and Notes.

At the top right hand is a green *design panel* upon which the profile of the dive can be
manipulated directly by dragging and clicking as explained below. This feature makes the
_Subsurface_ dive planner unique in ease of use.

At the bottom right is a text panel with a heading of _Dive Plan Details_. This is where the details of
the dive plan are provided in a way that can easily be copied to other software. This is also where
any warning messages about the dive plan are printed.

image::images/PlannerWindow1_f20.jpg["FIGURE: Dive planner startup window",align="center"]


=== Open circuit dives

-  Towards the centre bottom of the planner (circled in blue in the image above) is a dropbox with three options. Select the appropriate one of these:
 ** Open Circuit (the default)
 ** CCR
 ** pSCR

- Choose the Open Circuit option.
- In the top left-hand area of the planning screen, ensure that the constant dive parameters are
  appropriate. These are: Start date and time of the intended dive, Atmospheric Pressure and Altitude
  above sea level of the dive site. The atmospheric pressure can also be entered as an altitude
  in metres, assuming a sea-level atmospheric pressure of 1.013 bar.

- In the table labelled _Available Gases_, add the information of the cylinders to be used
  as well as the gas composition within that cylinder. This is done in a similar way as for
  <<cylinder_definitions,providing cylinder data for dive logs>>. Choose the cylinder type by
  double clicking the cylinder type and using the dropdown list, then specify the work
  pressure of this cylinder. By leaving the oxygen concentration (O2%) filed empty,
  the cylinder is assumed to contain air. Otherwise enter the oxygen and/or helium
  concentration in the boxes provided in this dialogue. Add additional cylinders by using the
  "+" icon to the top right-hand of the dialogue.

- The profile of the planned dive can be created in two ways:
 *  Drag the waypoints
    (the small white circles) on the existing dive profile in a way to represent the dive. Additional
    waypoints can be created by double-clicking the existing dive profile. Waypoints can be deleted
    by right-clicking a particular waypoint and selecting the _delete_ item from the resulting
    context menu.
 *  The most efficient way to create a dive profile is to enter the appropriate values into the table
    marked _Dive planner points_. The first line of the table represents the duration and the final
    depth of the descent from the surface. Subsequent segments describe the bottom phase of the dive.
    The _CC set point_ column is only relevant for closed circuit divers.
    The ascent is usually not specified because this is what the planner is supposed to calculate.
    Add additional segments to the profile by selecting the "+" icon at the top right hand of the
    table. Segments entered into the _Dive planner points_ table automatically appear in the *Dive
    Profile* diagram.

==== Recreational dives

Recreational mode is what comes closest to planning a dive based on the non-decompression limit (NDL).
It computes the maximal time a diver can stay at the current depth without incurring any mandatory decompression
stops and without using more than the existing gas (minus a reserve). The planner automatically takes
into account the nitrogen load incurred in previous dives. But conventional dive tables are also used in a
way that can take into account previous dives. Why use a dive planner for recreational dives? Using
recreational dive tables, the maximum depth of a dive is taken into account. However, few dives are
undertaken at a constant depth corresponding to the maximum depth (i.e. a "square" dive profile). This means
that dive tables overestimate the nitrogen load incurred during previous dives. The _Subsurface_
dive planner calculates nitrogen load according to the real dive profiles of all uploaded previous dives,
in a similar way as dive computers calculate nitrogen load during a dive. This means that the diver gets 'credit'
in terms of nitrogen loading for not remaining at maximum depth during previous dives, enabling planning of a
longer subsequent dive. For the planner to work it is therefore crucial to upload all previous dives
onto _Subsurface_ before performing dive planning.

To plan a dive, the appropriate settings need to be defined.

- Ensure that the date and time is set to that of the intended dive. This allows calculation of
the nitrogen load incurred during previous dives.

- Immediately under the heading _Planning_ are two checkboxes _Recreational_ and _Safety Stop_.
  Check these two boxes.

- Then define the cylinder size,
  the gas mixture (air or % oxygen) and the starting cylinder pressure in the top left-hand
  section of the planner under _Available gases_.

- The planner calculates whether the specified cylinder contains enough air/gas to complete
  the planned dive. In order for this to be realistic, under _Gas options_, specify an appropriate
  surface air consumption (SAC) rate for _Bottom SAC_. Suitable values are between 15 l/min and 30 l/min,
  with novice divers or difficult dives requiring SAC rates closer to 30l/min.

- Define the amount of gas that the cylinder must have at the end of the bottom section of the
  dive just before ascent. A value of 50 bar is often used. The reason for this reserve gas is to provide for the possible
  need to bring one's buddy to the surface using gas sharing. How much gas is used in
  sharing depends on the depth of the ascent. This can be a bit hard to estimate, so most agencies assume a
  fixed amount of gas, or actually of pressure e.g. 40 or 50 bar or 25% or 33% (rule of thirds). But _Subsurface_ can do better
  because it knows about the ascent and that is why we add the amount of gas during the ascent (i.e. the "deco gas“).
  Subsurface still uses a fixed pressure „reserve“ but that is supposed to be for the additional gas used around the realisation
  that there is a problem and one's pulse rate goes up when one starts to buddy breathe. This reserve amount is user configurable.

- Define the depth of the dive by dragging the waypoints (white dots) on the dive profile or
  (even better) defining the appropriate depths using the table under _Dive planner points_ as
  desribed under the previous heading. If
  this is a multilevel dive, set the appropriate dive depths to represent the dive plan by adding
  waypoints to the dive profile or by adding appropriate dive planner points to the _Dive Planner Points_
  table. _Subsurface_ will automatically extend the bottom section of the dive to the maximum
  duration within the no-decompression limits (NDL).

- The ascent speed can be changed. The default ascent speeds are those considered safe for recreational
  divers.

The dive profile in the planner indicates the maximum dive time within no-deco limits using the
Bühlmann ZH-L16 algorithm and the gas and depth settings specified as described above. The _Subsurface_ planner
allows rapid assessment of dive duration as a function of dive depth, given the nitrogen load incurred during previous dives. The
dive plan includes estimates of the amount of air/gas used, depending on the cylinder settings specified
under _Available gases_. If the initial cylinder pressure is set to 0, the dive duration shown is the
true no-deco limit (NDL) without taking into account gas used during the dive. If the surface above the dive profile is RED
it means that recreational dive limits are exceeded and either the dive duration or the dive depth needs to be reduced.

Below is an image of a dive plan for a recreational dive at 30 metres. Although the no-deco limit (NDL) is 23
minutes, the duration of the dive is limited by the amount of air in the cylinder, reflected by the information in the
text box at the bottom right of the panel that requires sufficient air for buddy-sharing during the ascent.

image::images/rec_diveplan.jpg["FIGURE: A recreational dive plan: setup",align="center"]

==== Non-recreational open circuit dives, including decompression

Non-recreational dive planning involves exceeding the no-deco limits and/or using multiple breathing gases.
Such dives are planned in three stages:

*a) Nitrogen management*: This is performed by specifying the rates for descent and ascent,
as well as the deco model (GFLow, GFHigh or Conservatism level) under the headings _Rates_ and _Planning_
to the bottom left of the planning screen. Two deco models are supported the Bühlmann model and the VPM-B
model. Select one of the two models. When selecting the Bühlmann model, the gradient factors (GF_high and GF_low
need to be specified. Initially, the GFHigh and GFLow values in the _Preferences_
panel of _Subsurface_ is used. If these are changed within the planner (see _Gas Options_ within
the planner), the new values are
used without changing the original values in the _Preferences_. Gradient Factor settings strongly affect the calculated ceilings and their depths.
A very low GFLow value brings about decompression stops early on during the dive.
 ** For more information about Gradient factors, see the section on xref:S_GradientFactors[Gradient Factor Preference settings].

If the VPM-B model is selected, the Conservatism_level needs to be specified on a scale of 0 (least conservative) to 4 (most conservative).
This model tends to give deco stops at deeper levels than the Bühlmann model and often results in slightly shorter
dive durations than the Bühlmann model. When selecting one of these models, keep in mind that they are NOT exact physiological models but
only mathematical models that appear to work in practice.

For more information external to this manual see:

 * link:http://www.tek-dive.com/portal/upload/M-Values.pdf[Understanding M-values by Erik Baker, _Immersed_ Vol. 3, No. 3.]
 * link:http://www.rebreatherworld.com/general-and-new-to-rebreather-articles/5037-gradient-factors-for-dummies.html[Gradient factors for dummies, by Kevin Watts]
 * link:http://www.amazon.com/Deco-Divers-Decompression-Theory-Physiology/dp/1905492073/ref=sr_1_1?s=books&ie=UTF8&qid=1403932320&sr=1-1&keywords=deco+for+divers[_Deco for Divers_, by Mark Powell (2008). Aquapress] Southend-on-Sea, UK. ISBN 10: 1-905492-07-3.
An excellent non-technical review that discusses both the Bühlmann deco model and the VPM-B model.

The ascent rate is critical for nitrogen off-gassing at the end of the dive and is specified
for several depth ranges, utilising the average (or mean) depth as a yardstick. The mean depth
of the dive plan is indicated by a light grey line on the dive profile. Ascent rates
at deeper levels are often in the range of 8-12 m/min, while ascent rates near the surface are
often in the range of 4-9 m/min. The descent rate is also specified. If the option _Drop to first depth_
is activated, then the descent phase of the planned dive will be at the maximal descent rate specified
in the _Rates_ section of the dive setup.

*b) Oxygen management*: In the *Gas Options* part of the dive specification, the maximum partial
pressure for oxygen needs to be specified for the
bottom part of the dive (_bottom po2_) as well as for the decompression part of the dive (_deco po2_).
The most commonly
used values are 1.4 bar for the bottom part of the dive and 1.6 bar for any decompression
stages. Normally, a partial pressure of 1.6 bar is not exceeded. PO2 settings and the depth at which switching to a gas takes place can also be edited in the
_Available Gases_ dialog. Normally the planner decides on switching to a new gas when, during
ascent, the partial pressure of the new gas has increased to 1.6 bar.

*c) Gas management*: With open-circuit dives this is a primary consideration. One needs to keep within the limits of the amount of gas within the dive
cylinder(s), allowing for an appropriate margin for a safe return to the surface, possibly
sharing with a buddy. Under the _Gas Options_ heading, specify the best (but conservative) estimate
of your surface-equivalent air consumption (SAC, also termed RMV) in
litres/min (for the time being, only SI units are supported).  Specify the SAC during the
bottom part of the dive (_bottom SAC_) as well as during the decompression or safety stops of the
dive (_deco SAC_). Values of 15-30 l/min are common. For good gas management, a thumbsuck guess
is not sufficient and one needs to
monitor one's gas consumption on a regular basis, dependent on different dive conditions and/or equipment.
The planner calculates the total volume of gas used during the dive and issues a warning
if one exceeds the total amount of gas available. Good practice demands that one does not dive to
the limit of the gas supply but that an appropriate reserve is kept for unforeseen circumstances.
For technical diving, this reserve can be up to 66% of the total available gas.

Now (at last) one can start the detailed time-depth planning of the dive. _Subsurface_ offers a unique
graphical interface for performing this part of the planning. The mechanics of doing this is
similar to hand-entering a dive profile in the dive log part of _Subsurface_. Upon activating the
planner, a default dive of depth 15 m for 40 min is offered in the bue design surface to the top
right hand of the screen. The white dots (waypoints) on the
profile can be dragged with a mouse. Create more waypoints by double-clicking on the profile
line and ensuring that the profile reflects the intended dive. Drag the waypoints to represent
the depth and duration of the dive. It is NOT necessary to specify the ascent part of the dive
since the planner calculates this, based on the settings that have been specified.
If any of the management limits (for nitrogen, oxygen or gas) is exceeded, the surface
above the dive profile changes from BLUE to RED.

Each waypoint on the dive profile creates a _Dive Planner Point_ in the table on the
left of the dive planner panel. Ensure that the _Used Gas_ value in each row
of that table corresponds to one of the gas mixtures specified in the _Available Gases_ table.
Add new waypoints until the main features of the dive have been completed, e.g. the
bottom time segment and deep stops (if these are implemented). Leave the remaining
waypoints on the ascent to _Subsurface_. In most cases _Subsurface_
computes additional way points in order to fulfil decompression requirements for that
dive. A waypoint can be moved by selecting that waypoint and by using the arrow keys.
The waypoints listed in the _Dive Planner Points_ dialogue can be edited by hand in
order to obtain a precise presentation of the dive plan. In fact, one can create the
whole dive profile by editing the _Dive Planner Points_ dialog.

Indicate any changes in gas cylinder used by indicating gas changes as explained
in the section <<S_CreateProfile,hand-creating a dive profile>>. These changes should
reflect the cylinders and gas compositions defined in the table with _Available Gases_.
If two or more gases are used, automatic gas switches will be suggested during the ascent to
the surface. However, these changes can be deleted by right-clicking the gas change and by
manually creating a gas change by right-clicking on the appropriate
waypoint.

A non-zero value in the "CC set point" column of the table of dive planner points
indicates a valid setpoint for oxygen partial pressure and that the segment
is dived using a closed circuit rebreather (CCR). If the last manually entered
segment is a CCR segment, the decompression phase is computed assuming the diver
uses a CCR with the specified set-point. If the last segment (however
short) is on open circuit (OC, indicated by a zero set-point) the
decompression is computed in OC mode. The planner only considers gas
changes in OC mode.

Below is an example of a dive plan to 45m using EAN26, followed by an ascent using EAN50
and using the settings as described above.

image::images/DivePlanner2_f20.jpg["FIGURE: Planning a dive: setup",align="center"]

Once the above has been completed, one can save it by clicking the _Save_ button
towards the top middle of the planner. The saved dive plan will appear
in the *Dive List* panel of _Subsurface_.

*The dive plan details*

On the bottom right of the dive planner, under _Dive Plan Details_, the exact details
of the dive plan are provided. These details may be modified by checking any of the
options under the _Notes_ section of the dive planner, immediately to the left
of the _Dive Plan Details_. If a _Verbatim dive plan_
is requested, a detailed sentence-level explanation of the dive plan is given. If any
of the management specifications have been exceeded during the planning, a warning
message is printed underneath the dive plan information.

If the option _Display segment duration_ is checked, then the duration of each depth
level is indicated in the _Dive Plan Details_. This duration INCLUDES the transition
time to get to that level. However, if the _Display transition in deco_ option is checked,
the transitions are shown separately from the segment durations at a particular level.

=== Planning pSCR dives

To plan a dive using a passive semi-closed rebreather (pSCR), select _pSCR_ rather than
_Open circuit_ in the dropdown list.
The parameters of the pSCR dive can be set by selecting  _File ->   Preferences ->   Graph_
from the main menu, where the gas consumption calculation takes into account the pSCR dump
ratio (default 10:1) as well as the metabolism rate. The calculation also takes the oxygen drop
accross the mouthpiece of the rebreather into account. If the
pO~2~ drops below what is considered a save value, a warning appears in the _Dive plan
details_. A typical pSCR configuration is with a single cylinder and one or more bail-out
cylinders. Therefore the setup of the _Available gases_ and the _Dive planner points_ tables
are very similar to that of a CCR dive plan, described below. However, no oxygen setpoints
are specified for pSCR dives. Below is a dive plan for a pSCR dive. The dive is comparable
to that of the CCR dive below, but note the longer ascent duration due to the lower oxygen
in the loop due to the oxygen drop across the mouthpiece of the pSCR equipment.

image::images/Planner_pSCR1_f20.jpg["FIGURE: Planning a pSCR dive: setup",align="center"]


=== Planning CCR dives

To plan a dive using a closed circuit rebreather, select the _CCR_ option in the dropdown
list, circled in blue in the image below.

*Available gases*: In the _Available gases_ table, enter the cylinder information for the
diluent cylinder and for any bail-out cylinders. Do NOT enter the information for the oxygen
cylinder since it is implied when the _CCR_ dropdown selection is made.

*Entering setpoints*: Specify a default setpoint in the Preferences tab, by selecting _File ->  Preferences ->  Graph_ from
the main menu. All user-entered segments in the _Dive planner points_ table
use the default setpoint value. Then, different setpoints can be specified for dive segments
in the _Dive planner points_ table. A zero setpoint
means the diver bails out to open circuit mode for that segment. The decompression is always calculated
using the setpoint of the last manually entered segment. So, to plan a bail out ascent for a
CCR dive, add a one-minute dive segment to the end with a setpoint value of 0. The decompression
algorithm does not switch deco-gases automatically while in CCR mode (i.e. when a positive setpoint is specified) but,
of course, this is calculated for bail out ascents.

The dive profile for a CCR dive may look something like the image below.

image::images/Planner_CCR1_f20.jpg["FIGURE: Planning a CCR dive: setup",align="center"]

Note that, in the _Dive plan details_, the gas consumption for a CCR segment is not calculated,
so gas consumptions of 0 litres are the norm.

[[S_Replan]]
=== Modifying an existing dive plan

Normally, when a dive plan has been saved, it is accessible from the *Dive List*, like any
other dive log. Within the *Dive List* there is not a way to change a saved dive plan.
To perform changes to a dive plan, select it on the *Dive List*. Then, in the main menu,
select _Log ->  Re-plan dive_. This will open the selected dive plan within the dive planner,
allowing changes to be made and saved as usual.

In addition there is the option "Save new". This keeps the original
planned dive and adds a (possibly modified) copy to the dive list. If
that copy is saved with the same start time as the original, the two
dives are considered two versions of the same dive and do not
influence other each during decompression calculation (see next section).

=== Planning for repetitive dives

Repetitive dives can easily be planned if the dates and start times of the
repetitive dive set
is specified appropriately in the top left-hand _Start Time_ field. _Subsurface_
calculates the gas loading figures correctly and the effect of the first dive is
evaluated on later dives.

If one has just completed a long/deep dive and is planning
another dive, then highlight, in the *Dive List*, the dive that has just been completed
and then activate the planner. Depending on the start time of the planned dive,
the planner takes into account the gas loading incurred during the completed dive
and allows planning within these limitations.

If only a few standard configurations are used (e.g. in GUE), then a template dive can
be created conforming to one of the configurations. If one now wishes to plan a dive using
this configuration, just highlight the template dive in the *Dive List* and activate the
planner: the planner takes into account the configuration in the highlighted dive.

=== Printing the dive plan

Selecting the _Print_ button in the planner allows printing of the  _Dive Plan Details_
for wet notes. Alternatively one can cut and paste the _Dive Plan Details_ for
inclusion in a text file or word processing document.

Dive plans have many characteristics in common with dive logs (dive profile, dive notes, etc).
After a dive plan has been saved, the dive details and gas calculations are saved in
the *Notes* tab. While a dive plan is being designed, it can be printed using
the _Print_ button in the dive planner. This prints the dive details and gas calculations
in the _Dive Plan Details_ panel of the dive planner. However, after the plan has been saved, it is
represented in a way very similar to a dive log and the gas calculations cannot be
accessed in the same way as during the planning process. The only way to print the
dive plan is to use the _File ->  Print_ facility on the main menu in the
same way as for dive logs or by copy and paste to a word processor.

== Description of the Subsurface Main Menu items

This section describes the functions and operation of the items in the Main Menu
of Subsurface. Several of the items below are links to sections of this manual
dealing with the appropriate operations.

=== File
- <<S_NewLogbook,_New Logbook_>> - Close the currently open dive logbook and
  clear all dive information.
- _Open logbook_ - This opens the file manager in order to select a dive
  logbook to open.
- _Open cloud storage_ - Open the dive log previously saved in <<S_Cloud_storage,_Cloud storage_>>.
- _Save_ - Save the dive logbook that is currently open.
- _Save to cloud storage_ - Save the current dive log to <<S_Cloud_storage,_Cloud storage_>>.
- _Save as_ - Save the current logbook under a different file name.
- _Close_ -  Close the dive logbook that is currently open.
- <<S_ExportLog,_Export_>> -  Export the currently open dive logbook (or
  the selected dives in the logbook) to one of several formats.
- <<S_PrintDivelog,_Print_>> -  Print the currently open logbook.
- <<S_Preferences,_Preferences_>> -  Set the _Subsurface_ preferences.
- <<S_FindMovedImages, _Find moved images_>> - If photos taken during dives have been moved to
      a different disk or directory, locate them and link them to the appropriate dives.
- <<S_Configure,_Configure dive computer_>> - Edit the configuration of a dive computer.
- _Quit_ - Quit _Subsurface_.

=== Import
- <<S_ImportDiveComputer,_Import from dive computer_>> - Import dive information
  from a dive computer.
- <<Unified_import,_Import Log Files_>> - Import dive information from a file in
  in a _Subsurface_-compatible format.
- <<S_Companion,_Import GPS data from Subsurface web service_>> - Load GPS
  coordinates from the _Subsurface_ mobile phone app.
- <<S_ImportingDivelogsDe,_Import from Divelogs.de_>> - Import dive information
  from _www.Divelogs.de_.

=== Log
- <<S_EnterData,_Add Dive_>> - Manually add a new dive to the *Dive List* panel.
- _Edit dive_ - Edit a dive of which the profile was entered by hande and not from a dive computer.
- <<S_DivePlanner,_Plan Dive_>> - This feature allows the planning of dives.
- <<S_Replan,_Edit dive in planner_>> - Edit a dive plan that has been saved into the *Dive List*.
- <<S_CopyComponents,_Copy dive components_>> - By selecting this option, one can copy information
  from several fields of a dive log onto the clipboard.
- _Paste dive components_ - Paste, into the selected dives in the *Dive List*,
  the information copied using the _Copy dive components_ option.
- <<S_Renumber,_Renumber_>> - Renumber the dives listed in the *Dive List*
  panel.
- <<S_Group,_Auto Group_>> - Group the dives in the *Dive List* panel into dive
  trips.
- <<S_DeviceNames,_Edit Device Names_>> - Edit the names of dive computers to facilitate your logs.
- <<S_Filter,_Filter divelist_>> - Select only some dives, based on specific tags or dive criteria.

=== View
- <<S_ViewPanels,_All_>> - View the four main _Subsurface_ panels
  simmultaneously.
- <<S_ViewPanels,_Dive List_>> - View only the *Dive List* panel.
- <<S_ViewPanels,_Profile_>> - View only the *Dive Profile* panel.
- <<S_ViewPanels,_Info_>> - View only the *Notes* panel.
- <<S_ViewPanels,_Globe_>> - View only the *World Map* panel.
- _Yearly Statistics_ - Display summary statistics about dives during this and past
  years.
- _Prev DC_ - If a single dive was logged from more than one dive computer, switch to data from
   previous dive computer.
- _Next DC_ - Switch to next dive computer.
- _Full Screen_ - Toggles Full Screen mode.

=== Share on
- <<S_Facebook,_Facebook_>> - Share the currently selected dive on your Facebook timeline.


=== Help
- _About Subsurface_ - Show a panel with the version number of _Subsurface_ as
  well as licensing information.
- _Check for updates_ - Find out whether a newer version of Subsurface is available
  on the http://subsurface-divelog.org/[_Subsurface_ web site].
- <<S_UserSurvey,_User survey_>>  - Help to make _Subsurface_ even better by taking part in our user survey
  or by completing another survey if your diving habits have changed.
- _User manual_ - Open a window showing this user manual.



== APPENDIX A: Operating system specific information for importing dive information from a dive computer.

=== Make sure that the OS has the required drivers installed
[icon="images/icons/drivers.jpg"]
[NOTE]
The operating system of the desktop computer needs the appropriate drivers in
order to communicate with the dive computer in whichever way the dive
computer prefers (e.g. Bluetooth, USB, infra-red).

	* On Linux users need to have the correct kernel
	  module loaded. Most distributions will do this automatically, so the
	  user does not need to load kernel modules. However, some communication
	  protocols require an additional driver, especially for rarely used
	  technology such as infra-red.

	* On Windows, the OS should offer to download the correct
	  driver once the user connects the dive computer to the USB port and
	  operating system sees the equipment for the first time.

	* On a Mac users sometimes have to manually hunt for the correct
	  driver. For example the correct driver for the Mares Puck
	  devices or any other dive computer using a USB-to-serial interface
	  based on the Silicon Labs CP2101 or similar chip can be found as
	  _Mac_OSX_VCP_Driver.zip_ at the
http://www.silabs.com/support/pages/document-library.aspx?p=Interface&f=USB%20Bridges&pn=CP2101[Silicon Labs document and software repository].

[[S_HowFindDeviceName]]
=== How to Find the Device Name for USB devices and set its write permission
[icon="images/icons/usb.jpg"]
[NOTE]
When a user connects the dive computer by using a USB connector, usually
_Subsurface_ will either propose a drop down list that contains the
correct device name (or mount point for the Uemis Zurich), or it will
disable the device select drop down if no device name is needed at
all. In the rare cases where this doesn't work, here are some
suggestions of ways to find out what the device name is:

.On Windows:

Simply try COM1, COM2, etc. The drop down list should contain all connected COM
devices.

.On MacOS:

The drop down box should find all connected dive computers.

.On Linux:

There is a definitive way to find the port:

 - Disconnect the USB cable from the dive computer
 - Open a terminal
 - Type the command: 'dmesg' and press enter
 - Plug in the USB cable of the dive computer
 - Type the command: 'dmesg' and press enter

A message similar to this one should appear:

	usb 2-1.1: new full speed USB device number 14 using ehci_hcd
	usbcore: registered new interface driver usbserial
	USB Serial support registered for generic
	usbcore: registered new interface driver usbserial_generic
	usbserial: USB Serial Driver core
	USB Serial support registered for FTDI USB Serial Device
	ftdi_sio 2-1.1:1.0: FTDI USB Serial Device converter detected
	usb 2-1.1: Detected FT232BM
	usb 2-1.1: Number of endpoints 2
	usb 2-1.1: Endpoint 1 MaxPacketSize 64
	usb 2-1.1: Endpoint 2 MaxPacketSize 64
	usb 2-1.1: Setting MaxPacketSize 64
	usb 2-1.1: FTDI USB Serial Device converter now attached to ttyUSB3
	usbcore: registered new interface driver ftdi_sio
	ftdi_sio: v1.6.0:USB FTDI Serial Converters Driver

The third line from the bottom shows that the FTDI USB adapter is
detected and connected to +ttyUSB3+. This information can now be used in
the import settings as +/dev/ttyUSB3+ which directs Subsurface to the correct
USB port.

Ensuring that the user has write permission to the USB serial port:

On Unix-like operating systems the USB ports can only be accessed by users who
are members
of the +dialout+ group. If one is not root, one may not be a member of
that group and
will not be able to use the USB port. Let us assume one's username is 'johnB'.

 - As root, type: +usermod -a -G dialout johnB+  (Ubuntu users: +sudo usermod
-a -G dialout johnB+)
This makes johnB a member of the +dialout+ group.
 - Type: +id johnB+     This lists all the groups that johnB belongs to and
verifies that
the appropriate group membership has been created. The +dialout+ group should
be listed
among the different IDs.
 - Under some circumstances this change takes only effect (eg. on Ubuntu) after
one logs out and then logs in again.

With the appropriate device name (e.g. +dev/ttyUSB3+) and with write permission
to the USB
port, the dive computer interface can connect and one should be able to import
dives.


[[S_HowFindBluetoothDeviceName]]
=== Manually setting up Bluetooth enabled devices
[icon="images/icons/bluetooth.jpg"]
[NOTE]
For dive computers communicating through Bluetooth like the Heinrichs
Weikamp Frog or the Shearwater Predator, Petrel, and Nerd there is a
different procedure to get the devices name to communicate with
_Subsurface_. Follow these steps:

 * *For the dive computer, after enabling Bluetooth, ensure it is in Upload mode.*

For Bluetooth pairing of the dive computer, refer to the
manufacturer's user guide. When using a Shearwater Predator/Petrel/Nerd, select
_Dive Log ->  Upload Log_ and wait for the _Wait PC_ message.

 * *Pair the _Subsurface_ computer with the dive computer.*

==== On Windows:

Bluetooth is most likely already enabled. For pairing with the dive computer choose
_Control Panel ->  Bluetooth Devices ->  Add Wireless Device_.
This should bring up a dialog showing your dive computer (which should be in Bluetooth mode) and
allowing pairing. Right click on it and choose _Properties->  COM
Ports_ to identify the port used for your dive computer. If there are several
ports listed, use the one saying "Outgoing" instead of "Incoming".

For downloading to _Subsurface_, the _Subsurface_ drop-down list should contain
this COM port already. If not, enter it manually.

Note: If there are issues afterwards when downloading from the dive computer using
other software, remove the existing pairing with the dive computer.

==== On MacOS:

Click on the Bluetooth symbol in the menu bar and select _Set up
Bluetooth Device..._. The dive computer should then show up in the list of devices. Select it and go
through the pairing process. This step should only be needed once for
initial setup.

Once the pairing is completed the correct device is shown in the
'Device or Mount Point' drop-down in the _Subsurface_ *Import* dialog.

==== On Linux
Ensure Bluetooth is enabled on the _Subsurface_ computer.
On most common distributions this should be true out of the box and
pairing should be straight forward. For instance, Gnome3 shows a
Bluetooth icon on the right of the toolbar at the top of the screen.
Users have reported difficulties with some Bluetooth controllers.  If you have an onboard controller,
try that first.  It is simplest if you remove any USB Bluetooth dongles.  If you have a USB dongle that
came with your dive computer, try that before any others.

Setting up a connection to download dives from your Bluetooth-enabled device, such as the
_Shearwater Petrel_, is not yet an automated process and will generally require the command prompt.
It is essentially a three step process.

 - Enable the Bluetooth controller and pair your dive computer
 - Establish an RFCOMM connection
 - Download the dives with Subsurface

Ensure the dive computer is in upload mode. On the _Shearwater Petrel_,  _Petrel 2_, and _Nerd_
cycle through the menu, select 'Dive Log', then 'Upload Log'.  The display will read 'Initializing', then
'Wait PC 3:00' and will countdown.  Once the connection is established, the display reads 'Wait CMD ...'
and the countdown continues. When downloading the dive from Subsurface, the display reads 'Sending' then
'Sent Dive'.

To establish the connection, establish root access through +sudo+ or +su+.
The correct permission is required to download the dives in the computer. On most Linux systems this means becoming
a member of the dialout group (This is identical as for many dive computers using a Linux USB port, described
in the previous section). On the command terminal, enter:

+sudo usermod -a -G dialout username+

Then log out and log in for the change to take effect.

===== Enabling the Bluetooth controller and pairing your dive computer

Attempt to set up the Bluetooth controller and pair your dive computer using the graphical
environment of the operating system. After setting the dive computer to upload mode, click the Bluetooth icon in the system tray
and select 'Add new device'. The dive computer should appear. If asked for a password, enter 0000.
Write down or copy the MAC address of your dive computer - this needed later and should be in the form 	00:11:22:33:44:55.

If the graphical method didn't work, pair the device from the command line. Open a terminal
and use +hciconfig+ to check the Bluetooth controller status

	$ hciconfig
	hci0:	Type: BR/EDR  Bus: USB
		BD Address: 01:23:45:67:89:AB  ACL MTU: 310:10  SCO MTU: 64:8
		*DOWN*
		RX bytes:504 acl:0 sco:0 events:22 errors:0
		TX bytes:92 acl:0 sco:0 commands:21 errors:0

This indicates a Bluetooth controller with MAC address 01:23:45:67:89:AB, connected as hci0.
Its status is 'DOWN', i.e. not powered.  Additional controllers will appear as hci1, etc.
If there is not a Bluetooth dongle plugged in upon booting the computer, hci0 is probably the onboard.
Now power on the controller and enable authentication:

	sudo hciconfig hci0 up auth+  (enter password when prompted)
	hciconfig
	hci0:  Type: BR/EDR  Bus: USB
		BD Address: 01:23:45:67:89:AB  ACL MTU: 310:10  SCO MTU: 64:8
		*UP RUNNING PSCAN AUTH*
		RX bytes:1026 acl:0 sco:0 events:47 errors:0
		TX bytes:449 acl:0 sco:0 commands:46 errors:0

Check that the status now includes +'UP', 'RUNNING' AND 'AUTH'+.

If there are multiple controllers running, it's easiest to off the unused controller(s). For example, for +hci1+:

	sudo hciconfig hci1 down

Next step is to 'trust' and 'pair' the dive computer. On distros with Bluez 5, such as Fedora 22,
one can use a tool called +blutootctl+, which will bring up its own command prompt.

	bluetoothctl
	[NEW] Controller 01:23:45:67:89:AB localhost.localdomain [default]
	[bluetooth]# agent on
	Agent registered
	[bluetooth]# default-agent
	Default agent request successful
	[bluetooth]# scan on                        <----now set your dive computer to upload mode
	Discovery started
	[CHG] Controller 01:23:45:67:89:AB Discovering: yes
	[NEW] Device 00:11:22:33:44:55 Petrel
	[bluetooth]# trust 00:11:22:33:44:55        <----you can use the tab key to autocomplete the MAC address
	[CHG] Device 00:11:22:33:44:55 Trusted: yes
	Changing 00:11:22:33:44:55 trust succeeded
	[bluetooth]# pair 00:11:22:33:44:55
	Attempting to pair with 00:11:22:33:44:55
	[CHG] Device 00:11:22:33:44:55 Connected: yes
	[CHG] Device 00:11:22:33:44:55 UUIDs: 00001101-0000-1000-8000-0089abc12345
	[CHG] Device 00:11:22:33:44:55 Paired: yes
	Pairing successful
	[CHG] Device 00:11:22:33:44:55 Connected: no

If asked for a password, enter 0000. It's ok if the last line says 'Connected: no'. The important part
is the line above, +Pairing successful+.

If the system has Bluez version 4 (e.g. Ubuntu 12.04 through to 15.04), there is probably not a
+bluetoothctl+, but  a script called +bluez-simple-agent+ or just +simple-agent+.

	hcitool -i hci0 scanning
	Scanning ...
		00:11:22:33:44:55       Petrel
		bluez-simple-agent hci0 00:11:22:33:44:55

Once ther dive computer is pired, set up the RFCOMM connection

===== Establishing the RFCOMM connection

The command to establish an RFCOMM connection is:

+sudo rfcomm -i <controller> connect <dev> <bdaddr> [channel]+

- +<controller>+ is the Bluetooth controller, +hci0+.
- +<dev>+ is the RFCOMM device file, +rfcomm0+
- +<bdaddr>+ is the dive computer's MAC address, +00:11:22:33:44:55+
- +[channel]+ is the dive computer's Bluetooth channel we need to connect to.

If one omits it, channel 1 is assumed.  Based on a limited number of user reports,
the appropriate channel for the dive computer is probably:

- _Shearwater Petrel 2_: channel 5
- _Shearwater Nerd_: channel 5
- _Shearwater Petrel 1_: channel 1
- _Heinrichs-Weikamp OSTC Sport_: channel 1

E.g. to connect a _Shearwater Petrel 2_, set the dive computer to upload mode and enter:

	sudo rfcomm -i hci0 connect rfcomm0 00:11:22:33:44:55 5 (enter a password, probably 0000, when prompted)

This gives the response:

	Connected /dev/rfcomm0 to 00:11:22:33:44:55 on channel 5
	Press CTRL-C for hangup

To connect a _Shearwater Petrel 1+ or + HW OSTC Sport+, set the dive computer to upload mode and enter:

	sudo rfcomm -i hci0 connect rfcomm0 00:11:22:33:44:55   (enter a password, probably 0000, when prompted)
	Connected /dev/rfcomm0 to 00:11:22:33:44:55 on channel 1
	Press CTRL-C for hangup

If the specific channel the dive computer needs is not known, or the channel in the list above doesn't
work, the command +sdptool records+ should help determine the appropriate channel. The output
below is for a _Shearwater Petrel 2_.

	sdptool -i hci0 records 00:11:22:33:44:55
	Service Name: Serial Port
	Service RecHandle: 0x10000
	Service Class ID List:
		"Serial Port" (0x1101)
		Protocol Descriptor List:
		"L2CAP" (0x0100)
		"RFCOMM" (0x0003)
		Channel: 5

For a Bluetooth dive computer not in the list above, or if the channel listed is not correct, please
let the Subsurface developers know on the user forum or the developer mailing list _subsurface@subsurface-divelog.org_.

===== Download the dives with Subsurface
After establishing the RFCOMM connection and while the dive computer's upload mode countdown is still running, go to_Subsurface_, select _Import->Import from dive computer_ and enter appropriate Vendor (e.g. _Shearwater_), Dive Computer (_Petrel_), Device or Mount Point (_/dev/rfcomm0_) and click _Download_.




[[_appendix_b_dive_computer_specific_information_for_importing_dive_information]]

== APPENDIX B: Dive Computer specific information for importing dive data.

[[S_ImportUemis]]
=== Importing from Uemis Zurich

[icon="images/icons/iumis.jpg"]
[NOTE]
_Subsurface_ downloads the information
stored on the SDA (the built-in file system of the Uemis) including
information about dive spots and
equipment. Buddy information is not yet downloadable.
Things are very similar to a normal USB-connected dive computer
(the Uemis is one of those that recharge when connected to the USB port).
The main difference is that one does not enter a
device name, but instead the location where the UEMISSDA file system is
mounted once connected to the dive computer. On Windows this is a drive letter (
often 'E:' or 'F:'), on a Mac this is
'/Volumes/UEMISSDA' and on Linux systems this differs depending on the
distribution. On Fedora it usually is
'/var/run/media/<your_username>/UEMISSDA'. In all cases _Subsurface_
should suggest the correct location in the drop down list.

After selecting the above device name, download the
dives from the Uemis Zurich. One technical issue with the Uemis Zurich
download implementation (this is a Uemis firmware limitation, not a
_Subsurface_ issue) is that one cannot download more than about 40-50
dives without running out of memory on the SDA. This will usually only
happen the very first time one downloads dives from the Uemis Zurich.
Normally when downloading at the end of a day or even after a dive
trip, the capacity is sufficient. If _Subsurface_ displays an error
that the dive computer ran out of space the solution is straight
forward.  Disconnect the SDA, turn it off and on again, and reconnect
it. You can now retry (or start a new download session) and the
download will continue where it stopped previously. One
may have to do this more than once, depending on how many dives are
stored on the dive computer.

[[S_ImportingGalileo]]
=== Importing from Uwatec Galileo

[icon="images/icons/Galileo.jpg"]
[NOTE]
The Uwatec Galileo dive computers use infra red (IrDA) communication
between the dive computer and Subsurface. The Uwatec hardware uses
a USB dongle based on the serial infra-red (SIR) protocol and the
MSC7780 IrDA controller manufactured by MosChip
and marketed by Scubapro and some electronics companies.
Under Linux, the kernel
already provides for communication using the IrDA protocol. However,
the user additionally needs to load a driver for the IrDA interface
with the dive computer. The easiest way is to load the *irda-tools*
package from the http://irda.sourceforge.net/docs/startirda.html[Linux IrDA Project].
After the installation of the irda-tools, the *root user* can specify a device name
from the console as follows:
+irattach irda0+

After executing this command, Subsurface will recognise the Galileo
dive computer and download dive information.

Under Windows, a similar situation exists. Drivers for the MCS7780 are
available from some Internet web sites e.g.
http://www.drivers-download.com/Drv/MosChip/MCS7780/[www.drivers-download.com]. Windows-based IrDA
drivers for the Uwatec can also be downloaded from the ScubaPro web site, drivers being located on
the download page for the ScubaPro SmartTrak software.

For the Apple Mac, IrDA communication via the MCS7780 link is not
available for OSX 10.6 or higher.

[[S_ImportingDR5]]
=== Importing from Heinrichs Weikamp DR5

[icon="images/icons/HW_DR5.jpg"]
[NOTE]
When mounted as a USB drive the Heinrichs Weikamp DR5 saves a single UDDF file
for every dive.
Mark all the dives you'd like to import or open.
Note: The DR5 does not seem to store gradient factors nor deco information, so
for _Subsurface_ it is not possible to display them. Adjust the gradient
factors in the _Graph Settings_ in _Subsurface_ to generate a deco overlay in the
_Subsurface_ *Dive Profile* panel but please note that the deco calculated by
_Subsurface_ will most likely differ from the one displayed on the DR5.


[[S_ImportingXDeep]]
=== Importing from xDEEP BLACK

[icon="images/icons/HW_xdeepblack.jpg"]
[NOTE]
Each dive has to be individually saved as UDDF file using "Export UDDF" option in BLACK's logbook menu.
When mounted as a USB drive UDDF files are available in LOGBOOK directory.
Note: The xDEEP BLACK saves NDL time but does not seem to store gradient factors nor deco information, so
for _Subsurface_ it is not possible to display them. Adjust the gradient
factors in the _Graph Settings_ in _Subsurface_ to generate a deco overlay in the
_Subsurface_ *Dive Profile* panel but please note that the deco calculated by
_Subsurface_ will most likely differ from the one displayed on the xDEEP BLACK.


=== Importing from Shearwater Predator/Petrel/Nerd using Bluetooth

[icon="images/icons/predator.jpg"]
[NOTE]
Specific instructions for downloading dives using Bluetooth are  given in the section above, <<S_Bluetooth,_Connecting Subsurface to a Bluetooth-enabled dive computer_>>.

[[S_PoseidonMkVI]]
=== Importing from Poseidon MkVI Discovery

[icon="images/MkVI.jpeg"]
[NOTE]
Download of dive logs from the MkVI is performed using a custom communications
adapter and the _Poseidon PC Configuration Software_, obtained when purchasing
the MKVI equipment. The latter is a Windows application allowing configuration
of equipment and storage of dive logs. Communication between dive computer and
desktop computer utilises the IrDA infra-red protocol. Only data for one dive
can be downloaded at a time, comprising three files:

- Setup configuration for the dive and key dive parameters (file with a .txt
  extension)
- Dive log details (file with a .csv extension)
- Redbook format dive log (file with .cvsr extension). This is a compressed
  version of the dive log using a proprietary format.

_Subsurface_ accesses the .txt and the .csv files to obtain dive log information.


=== Importing from APD Inspiration/Evolution CCR

[icon="images/APDComputer.jpg"]
[NOTE]
The dive logs of an APD Inspiration or similar CCR dive computer are downloaded using
a communications adapter and _AP Communicator_, obtained when
purchasing the equipment. The dive logs can be viewed using the _AP Log Viewer_,
within Windows or Mac/OS. However, APD logs can be viewed and managed from within
_Subsurface_ (together with dives using many other types of dive computer). The
APD inspiration dive logs are imported into _Subsurface_ as follows:

- Download the dive using _AP Communicator_.
- Open a dive within the _AP Log Viewer_.
- Select the tab at the top of the screen, entitled "_Data_".
- With the raw dive log data show on the screen, click on "_Copy to Clipboard_".
- Open a text editor, e.g. Notepad (Windows) or TextWrangler (Mac).
- Copy the contents of the clipboard into the text editor and save the text file
  with a filename extension of _.apd_
- Within _Subsurface_, select _Import ->  Import log files_ to open the xref:Unified_import[universal import dialogue].
- In the dropdown list towards the bottom right of the dialogue (labled 'Filter:'), select "APD log viewer".
- On the list of file names select the _.apd_ file that has been created above. An import
  dialogue opens indicating the default settings for the data in the _.apd_ file. If any changes are required,
  do this as for xref:S_ImportingCSVDives[CSV imports].

image::images/APD_CSVimportF22.jpg["Figure: APD log viewer import",align="center"]

- The top left hand dropdown box in the import panel allows one to select the APD dive computer
  for which the dive log needs to be imported. The default it is DC1, _i.e._ the
  first of the two dive computers the APD uses. It is possible to sequentially
  import the data for both dive computers by first importing CD1 and then DC2.(*Hint*: The logs
  for the two dive computers are viewed by selecting _View  ->  Next DC_ from
  the Main Menu after the uploading has been completed)
- Click the _Ok_ button at the bottom of the import panel.

The APD dive log will appear within _Subsurface_. The dive computer-generated ceiling
generated by the Inspiration can be viewed by selecting the appropriate
button on the left of the *Dive Profile*. Cylinder pressure data are not logged
by the APD equipment but can be manually entered in the _Equipment_ Tab.

== APPENDIX C: Exporting Dive log information from external dive log software.

The import of dive log data from external dive log software is mostly performed
using
the dialogue found by selecting _Import_ from the Main Menu, then clicking on
_Import Log Files_. This is a single-step process, more information about which
can be found
xref:Unified_import[here.]
However, in some cases, a two-step process may be required:

1. Export the foreign dive log data to format that is accessible from
  _Subsurface_.
2. Import the accessible dive log data into _Subsurface_.

This appendix provides some information about approaches to export dive log
data from foreign
dive log software. The procedures below mostly apply to Linux and/or Windows.

[[S_ImportingDivesSuunto]]
=== Exporting from *Suunto Divemanager (DM3, DM4 or DM5)*
[icon="images/icons/suuntologo.jpg"]
[NOTE]
DiveManager is a MS Windows application for Suunto dive computers.
Divemanager 3 (DM3) is an older version of the Suunto software. More recent
Suunto dive computers use Divemanager version 4 or 5 (DM4 or DM5). The
different versions of Divemanager use different methods and different file naming
conventions to export dive log data.

*Divemanager 3 (DM3):*

1. Start 'Suunto Divemanager 3' and log in with the name containing the logs
2. Do not start the import wizard to import dives from the dive computer.
3. In the navigation tree on the left side of the program-window, select the appropriate
   dives.
4. Within the list of dives, select the dives you would like to import later:
	* To select certain dives: hold 'ctrl' and click the dive
	* To select all dives:  Select the first dive, hold down shift and
	  select the last dive
5. With the dives marked, use the program menu _File ->  Export_
6. The export pop-up will show. Within this pop-up, there is one field called 'Export Path'.
	* Click the browse button next to the field Export Path
		** A file-manager like window pops up
		** Navigate to the directory for storing the
   Divelog.SDE file
		** Optionally change the name of the file for saving
		** Click 'Save'
	* Back in the Export pop-up, press the button 'Export'
7. The dives are now exported to the file Divelog.SDE.

*Divemanager 4 (DM4) and Divemanager 5 (DM5):*

DM4 and DM5 use identical mechanisms for exporting dive logs.
To export a divelog from Divemanager one needs to locate the DM4/DM5 database
where the dives are stored. the user can either look for the original
database or make a backup of the dives. Both methods are described here.

Locating the Suunto DM4 (or DM5) database:

1. Start Suunto DM4/DM5
2. Select 'Help ->  About'
3. Click 'Copy' after text 'Copy log folder path to clipboard'
4. Now open Windows Explorer
5. Paste the address to the path box at the top of the File Explorer
6. The database is called DM4.db or DM5.db

Making a backup copy of the Suunto DM4/DM5 database:

1. Start Suunto DM4/DM5
2. Select 'File - Create backup'
3. From the file menu select the location and name for the backup, we'll
   use DM4 (or DM5) in here with the default extension .bak
4. Click 'Save'
5. The dives are now exported to the file DM4.bak (or DM5.bak)


=== Exporting from Atomic Logbook
[[Atomic_Export]]

[icon="images/icons/atomiclogo.jpg"]
[NOTE]
Atomic Logbook is a Windows software by Atomic Aquatics. It allows
downloading of dive information from Cobalt and Cobalt 2 dive computers.
The divelog is kept in a SQLite database at
C:\ProgramData\AtomicsAquatics\Cobalt-Logbook\Cobalt.db. This file can
be directly imported to Subsurface.


=== Exporting from Mares Dive Organiser V2.1
[[Mares_Export]]

[icon="images/icons/mareslogo.jpg"]
[NOTE]
Mares Dive Organiser is a Windows application. The dive log is kept as a
Microsoft SQL Compact Edition database with a '.sdf' filename extension. The
database includes all Dive Organiser-registered divers on the particular
computer and all Mares dive computers used. The safest way to obtain a copy
of the dive database is to export the information to another compatible format
which can be imported into _Subsurface_.

1. Within Dive Organiser, select
   _Database ->  Backup_ from the main menu and back up the database to the desk
   top.
   This creates a zipped file DiveOrganiserxxxxx.dbf.
2. Rename the file to
   DiveOrganiserxxxxx.zip. Inside the zipped directory is a file
   _DiveOrganiser.sdf_.
3. Extract the _.sdf_ file from the zipped folder to your Desktop.
4. The password for accessing the .zip file is _mares_.

[[S_ImportingDivingLog]]
=== Exporting from *DivingLog 5.0 and 6.0*

[icon="images/icons/divingloglogo.jpg"]
[NOTE]
The best way to bring your logs from DivingLog to Subsurface is to
convert the whole database. This is because other export formats do not
include all the details, and we would lack e.g. gas switches and
information of what units are used. With database import, all this
information is included and readily available for us.

To transfer all files from DivingLog to Subsurface, do the following:

1. In DivingLog open the 'File ->  Export ->  SQLite' menu
2. Select 'Settings' button
3. Set the 'RTF2Plaintext' to 'true'
4. Close the Settings dialog
5. Click 'Export' button and select the filename

Once this is done, open the saved database file with Subsurface and the
dives are automatically converted to our own format. Last step to do is
save the log file in Subsurface.

== APPENDIX D: Exporting a spreadsheet to CSV format
[[S_Appendix_D]]

Many divers keep a diving log in some form of a digital file, commonly a spreadsheet
with various fields of information. These logs can be easily imported into _Subsurface_ after the
spreadsheet is converted in a .CSV file.
This section explains the procedure to convert a diving logbook stored in a spreadsheet
to a .CSV file that will later be imported from _Subsurface_.
Creating a .CSV is a straightforward task, although the procedure is somewhat different
according to which spreadsheet program is used.

The first step is to organize the diving data in the spreadsheet, so that the first row
contains the names (or titles) of each column and the information for each dive is stored in a single row.
_Subsurface_ supports many data items (Dive #, Date,
Time, Duration, Location, GPS, Max Depth, Mean Depth, Buddy, Notes, Weight and Tags).
The user can organize dive data following a few simple rules:

1. Date: use one of the following formats: yyyy-mm-dd, dd.mm.yyyy, mm/dd/yyyy
2. Duration: the format should be minutes:seconds.
3. Unit system: only one unit system should be used (i.e., no mixture between imperial and metric units)
4. Tags and buddies: values should be separated using a comma.
5. GPS position: users must use decimal degrees, e.g. 30.22496 30.821798

=== _LibreOffice Calc_ and _OpenOffice Calc_

These are open source spreadsheet applications forming parts of larger open source office suite applications. The user interaction with _LibreOffice_ and _OpenOffice_ is very similar.
In Libreoffice Calc the time format should be set to minutes:seconds - [mm]:ss and dates should be set to one of: yyyy-mm-dd, dd.mm.yyyy, mm/dd/yyyy. A typical dive log may look like this:

image::images/LOffice_spreadsheetdata.jpg["FIGURE: Spreadsheet data",align="center"]

To export the data as a .CSV file from within LibreOffice click _File ->  Save As_. On the dialogue that comes up, select the _Text CSV (.csv)_ as the file type and select the option _Edit filter settings_.

image::images/LOffice_save_as_options.jpg["FIGURE: Save as options",align="center"]

After selecting _Save_, select the appropriate field delimiter (choose _Tab_ to prevent conflicts with the comma when using this as a decimal point), then select _OK_.

image::images/LOffice_field_options.jpg["FIGURE: Field options",align="center"]

One can double check the .CSV file by opening it with a text editor, and then import the dive data as explained on the section xref:S_ImportingCSVDives[Importing CSV dives].

=== Microsoft _Excel_

The field delimiter (called "_list separator_" in Microsoft manuals) is not accessible
from within _Excel_ and needs to be set through the _Microsoft Control Panel_. After changing the
separator character, all software on the Windows machine use the new character as a separator.
One can change the character back to the default character by following the same procedure, outlined below.

- In Microsoft Windows, click the *Start* button, and then select _Control Panel_ from the list on the right-hand side.
- Open the _Regional and Language Options_ dialog box.
- Do one of the following:
  ** In Windows 7, click the _Formats_ tab, and then click _Customize this format_.
  ** In Windows XP, click the _Regional Options_ tab, and then click _Customize_.
- Type a new separator in the _List separator_ box. To use a TAB-delimited file, type the word TAB in the box.
- Click _OK_ twice.

Below is an image of the _Control Panel_:

image::images/Win_SaveCSV2.jpg["FIGURE: Win List separator",align="center"]

To export the dive log in CSV format:

With the dive log opened in _Excel_, select the round Windows button at the top left, then _Save As_.

image::images/Win_SaveCSV1.jpg["FIGURE: Excel save as option",align="center"]

Click on the left-hand part of the _Save as_ option, NOT on the arrow on the right-hand. This brings up a dialogue for saving the spreadsheet in an alternative format. From the dropdown list at the bottom of the dialogue, marked _Save as Type:_, select _CSV(Comma delimited) (*.CSV)_. Ensure that the appropriate folder has been selected to save the CSV file into.

image::images/Win_SaveCSV3.jpg["FIGURE: Excel save CSV dialogue",align="center"]

Select the _Save_ button. The CSV-formatted file is saved into the folder that was selected. One can double check the .CSV file by opening it with a text editor, and then import the dive data as explained on the section xref:S_ImportingCSVDives[Importing CSV dives].

[[S_APPENDIX_E]]
== APPENDIX E: Writing a custom print template

_Subsurface_ provides a mechanism to create or modify templates for printing dive logs in order to
produce customised printouts of dive logs. Templates, written in HTML as well as a simple
Grantlee instruction set, are rendered to the print device by _Subsurface_.

Templates are accessed using the print dialogue (see image *B* below).

image::images/Print1_f22.jpg["FIGURE: Print dialogue",align="center"]

The buttons under the _Template_ dropdown box allows one to _Edit_, _Delete_,
_Import_ and to _Export_ templates (see image *A* above). New or modified templates are stored as HTML
files in the same directory as the dive log being processed. In order to create or modify
a template, select one of the templates from the template dropdown list in the print dialogue
(see image *B* above). Choose an existing template that resembles the final desired printout. Then select _Edit_.

The Edit Panel comprises three tabs:

image::images/Template1_f22.jpg["FIGURE: template edit dialogue",align="center"]

1) The _Style_ tab (image *A* above) controls the font, line spacing and colour template used for printing the dive log.
   The style attributes are editable. Choose one of the four colour palets used for colour printing.

2) The _Colors_ tab (image *B* above) allows editing the colours used for printing the dive log. The colours are highly
   customisable: the _Edit_ buttons in the _Colors_ tab allows choosing abritrary colours for different
   components of the dive log printout.

3) The _Template_ tab of the Edit Panel (see image below) allows creating a template using HTML as well as a few
   Grantlee programming primitives. Grantlee provides the ability to create and format HTML code in
   a highly simple but efficient way (see below). The HTML of the template can be edited and saved. The saved
   template is stored in the same directory as the dive being processed. By default, a _Custom_
   template is a skeleton with no specific print instructions. The informastion being printed
   needs to be specified and formatted in the by replacing the section marked with:
   "<!-- Template must be filled -->". Writing HTML code with Grantlee instructions allows unlimited
   freedom in determining what is printed an in which way it should be rendered.

image::images/Template2_f22.jpg["FIGURE:Template tab",align="center"]

One can adapt any of the existing templates and save it to the dive log directory. The standard templates (e.g. One dive, Six dives, Table) can be modified in this way. After completing the edits, use the _Export_ button in the print
dialogue to save the new template using a new template name.

To write a custom template the following elements must exist so that the template will be correctly handled and rendered.

=== Main dive loop
_Subsurface_ exports a dive list called (*dives*) to the _Grantlee_ backend. It is possible to iterate over the list as follows:

.template.html
....
	{% for dive in dives %}
		<h1> {{ dive.number }} </h1>
	{% endfor %}
....

.output.html
....
	<h1> 1 </h1>
	<h1> 2 </h1>
	<h1> 3 </h1>
....

Additional information about _Grantlee_ can be found http://www.grantlee.org/apidox/for_themers.html[here]

=== Grantlee exported variables
Only a subset of the dive data is exported:
|====================
|*Name*|*Description*
|number| (*int*) dive number
|id| (*int*) unique dive ID, should be used to fetch the dive profile
|date| (*string*) data of the dive
|time| (*string*) time of the dive
|location| (*string*) location of the dive
|duration| (*string*) duration of the dive
|depth| (*string*) depth of the dive
|divemaster| (*string*) divemaster data
|buddy| (*string*) buddy data
|airTemp| (*string*) air temperature of dive
|waterTemp| (*string*) water temperature of dive
|notes| (*string*) dive notes
|rating| (*int*) dive rating ranges from 0 to 5
|sac| (*string*) sac value
|tags| (*string*) all dive tags concatenate together
|gas| (*string*) used gas cylinder
|=====================

_Subsurface_ also exports *template_options* data. This data must be used as _CSS_ values to provide a dynamically
editable template. The exported data is shown in the following table:
|====================
|*Name*|*Description*
|font| (*string*) font family
|borderwidth| (*int*) border-width value dynamically calculated as 0.1% of the page width with minimum value of 1px
|font_size| (*double*) size of fonts in vw, ranges between 1.0 and 2.0
|line_spacing| (*double*) distance between text lines, ranges between 1.0 and 3.0
|color1| (*string*) background color
|color2| (*string*) primary table cell color
|color3| (*string*) secondary table cell color
|color4| (*string*) primary text color
|color5| (*string*) secondary text color
|color6| (*string*) border colors
|=====================

.template.html
....
	border-width: {{ template_options.borderwidth }}px;
....

.output.html
....
	border-width: 3px;
....

Another variable that _Subsurface_ exports is *print_options*. This variable contains a single member:
|=====================
|*Name*|*Description*
|grayscale | Use _CSS_ filters to convert the page into grayscale (should be added to body style to enable printing grayscale prints)
|=====================


.template.html
....
	body {
		{{ print_options.grayscale }};
	}
....

.output.html
....
	body {
		-webkit-filter: grayscale(100%);
	}
....

=== Defined CSS selectors

As the dive profile is placed after rendering, _Subsurface_ uses a special _CSS_ selectors to do some searches
in the HTML output. The _CSS_ selectors in the following table should be added.

|====================
|*Selector*|*Type*|*Description*
|dive_{{ dive.id }} | id | is used to fetch the relevant dive profile
|diveProfile | class | each div that will contain a dive profile should have this class selector in addition to the dive_{{ dive.id }} id selector
|dontbreak | class | prevents the div with this class to be divided into two pages, this can be used
in flow layout templates only (when data-numberofdives = 0)
|=====================

IMPORTANT: Rendering dive profiles is not supported for flow layout templates (when data-numberofdives = 0).

=== Special attributes

There are two ways of rendering- either rendering a specific number of dives in each page or make _Subsurface_ try to
fit as much dives as possible into one page (_flow_ rendering).

The *data-numberofdives* data attribute is added to the body tag to set the rendering mode

- render 6 dives per page:

....
	<body data-numberofdives = 6>
....

- render as much dives as possible:

....
	<body data-numberofdives = 0>
....

IMPORTANT: All CSS units should be in relative lengths only, to support printing on any page size.

== APPENDIX F: FAQs.
[[S_APPENDIX_F]]
=== Subsurface appears to miscalculate gas consumption and SAC
[[SAC_CALCULATION]]
'Question': I dived with a 12.2 l tank, starting with 220 bar and ending with 100 bar, and I calculate a different SAC compared what _Subsurface_ calculates. Is _Subsurface_
miscalculating?

'Answer': Not really. What happens is that _Subsurface_ actually calculates gas
consumption differently - and better - than you expect.
In particular, it takes the incompressibility of the gas into account.
Traditionally, Gas consumption and SAC should be:
+consumption = tank size x (start pressure - end pressure)+

and that's true for an ideal gas, and it's what you get taught in dive theory.
But an "ideal gas" doesn't actually exist, and real gases actually don't compress
linearly with pressure. Also, you are missing the fact that one atmosphere of
pressure isn't actually one bar.
So the *real* calculation is:

+consumption = (amount_of_air_at_beginning - amount_of_air_at_end)+

where the amount of air is *not* just "tank size times pressure in bar".
It's a combination of: "take compressibility into account" (which is a fairly
small issue under 220 bar - you'll see more differences when you do high-pressure
tanks with 300bar) and "convert bar to atm" (which is the majority of your discrepancy).
Remember: one ATM is ~1.013 bar, so without the compressibility, your gas use is:

+12.2*((220-100)/1.013)+

which is about 1445, not 1464. So there was 19 l too much in your simple
calculation that ignored the difference between 1 bar and one ATM.
The compressibility does show up above 200 bar, and takes that 1445 down
about eight litres more, so you really did use only about 1437 l of air at surface pressure.

So be happy: your SAC really is better than your calculations indicated.
Or be sad: your cylinder contains less air than you thought it did.
And as mentioned, the "contains less air than you thought it did" really
starts becoming much more noticeable at high pressure. A 400 bar really does not
contain twice as much air as a 200 bar one. At lower pressures, air acts pretty much like an ideal gas.

=== Some dive profiles have time discrepancies with the recorded samples from my dive computer...

_Subsurface_ ends up ignoring surface time for many things (average depth, divetime, SAC, etc).
'Question':  Why do dive durations in my dive computer differ from that given by _Subsurface_?

'Answer': For example, if you end up doing a weight check (deep enough to trigger the "dive started")
but then come back up and wait five minutes for your buddies, your dive computer may say
that your dive is 50 minutes long - because you have fifty minutes worth of samples - but
subsurface will say it's 45 minutes - because you were actually diving for 45 minutes.
It's even more noticeable if you do things like divemastering the initial OW dives, when
you may stay in the water for a long time, but spend most of it at the surface. And then
you don't want that to count as some kind of long dive”.

=== Some dive profiles are missing from the download

[[DC_HISTORY]]
'Question': I cannot download all my dives, only the most recent ones
even though my dive computer's manual states that it records history of
e.g. 999 dives.

'Answer': Dive history is different than the dive profiles on the log.
The history only keeps track of the total number of dives and total
amount of time spent below surface. The logs, on the other hand, store
the dive profile, but they have limited amount of memory to do so. The
exact amount of dive profiles that can be stored on the device depend on
sample interval and duration of the dives. Once the memory is full the
oldest dives get overwritten with new dives. Thus we are only able to
download the last 13, 30 or 199 dives.

If you have downloaded your dives to different dive logging software
before they were overwritten, there is a high chance that Subsurface can
import these. However, if the logs are only on your dive computer, they
cannot be salvaged after being over written by new dives.