source: git/doc/manual.sgml @ 10909c2

<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V4.1//EN" [
<!ENTITY man.aven SYSTEM "aven.sgml">
<!ENTITY man.3dtopos SYSTEM "3dtopos.sgml">
<!ENTITY man.cad3d SYSTEM "cad3d.sgml">
<!ENTITY man.cavern SYSTEM "cavern.sgml">
<!ENTITY man.diffpos SYSTEM "diffpos.sgml">
<!ENTITY man.dump3d SYSTEM "dump3d.sgml">
<!ENTITY man.extend SYSTEM "extend.sgml">
<!ENTITY man.sorterr SYSTEM "sorterr.sgml">
]>

<!--
FIXME:

3dfile title:
defaults to a list of the leafnames of the <filename>.svx</filename> files specified on the
command line (with any paths and extensions removed).
.
e.g.: cavern entrance.svx \data\2ndpart.svx
.
would give a surveytitle of 'entrance 2ndpart'.
.
but this may change...

FIXME todo:
mark-up of Windows Windows NT etc?
section on "design philosophy"

level sump fudge:

*begin
*data cartesian from to dx dy dz
*sd dx dy 100 metres
*sd dz 0.001 metres
; upstream - downstream
nuiping.gowiththeflow.129 dachao.upstream.105 0 0 0 ; last number is drop in height across the sump
*end

``Quick start'' section

- install (by OS): unpacking, configuration (language, where support files live)

- lead people through entering and processing
a sample survey.  Take examples from surveying books and real surveys.


<Para>The other really important commands apart from *BEGIN, *END, and
*INCLUDE are *EQUATE and *FIX.
</Para>

<Para>*EQUATE is used to join surveys together, e.g.
</Para>

<programlisting>*equate entrance.6 adrian.1</programlisting>

<Para>
indicates that station 6 of the entrance survey was used as
the station 1 of the Adrian's Route survey.
</Para>

<Para>*FIX is for fixing control points - for example:
</Para>

<programlisting>
*fix 161.entrance.1    0  0  1780</programlisting>

<Para>fixes the 1st point of the 'entrance' survey at the coordinates
0 (east-west), 0 (north-south), 1780 (altitude).
</Para>


<term>node</term>
<listitem><para>when talking about the survey network, we talk about an
<emphasis>n</emphasis>-node to describe the number of connections to
a station.  So a 1-node is a station with only 1 leg to or from it
- i.e. The end of a passage or survey. A
2-node is a typical station along a passage with a survey leg coming
into it, and one going out.  A 3-node is a station with three legs
joining it, e.g. at a T-junction. And so on.
</para>

-->

<article Status="draft" id="index">
 <articleinfo>
  <Title><Application>Survex</Application> <!--VERSION-->1.2.31 Manual</Title>
  <AuthorGroup>
   <Author>
    <FirstName>Olly</FirstName>
    <SurName>Betts</SurName>
    <AuthorBlurb><Para>
      Olly Betts wrote most of <Application>Survex</Application>.
    </Para></AuthorBlurb>
    <Affiliation>
     <Address><Email>olly@survex.com</Email></Address>
    </Affiliation>
   </Author>
   <Author>
    <SurName>Wookey</SurName>
    <AuthorBlurb><Para>
      Wookey is a small furry creature.
    </Para></AuthorBlurb>
    <Affiliation>
     <Address><Email>wookey@survex.com</Email></Address>
    </Affiliation>
   </Author>
  </AuthorGroup>
  <copyright>
   <year>1998-2016</year>
   <holder role="mailto:olly@survex.com">Olly Betts</holder>
  </copyright>
  <Abstract>
   <Para>
    This is the manual for <Application>Survex</Application> - an open-source software package for
    cave surveyors.
   </Para>
  </Abstract>
 </articleinfo>

<Sect1><Title>Introduction</Title>
<?dbhtml filename="intro.htm">

<Para>
This section describes what <Application>Survex</Application> is, and outlines the scope of this
manual.
</Para>

<Sect2><Title>About <Application>Survex</Application></Title>

<Para><Application>Survex</Application> is a multi-platform open-source cave surveying
package.
Version 1.2 runs on UNIX, Microsoft Windows, and Mac OS X.
We're investigating support for phones and tablets.
</Para>

<Para>We are well aware that not everyone has access to super hardware
- often surveying projects are run on little or no budget and any
computers used are donated.  We aim to ensure that <Application>Survex</Application> is
feasible to use on low-spec machines.  Obviously it won't be as
responsive, but we intend it to be usable.
Please help us to achieve this by giving us some feedback
if you use <Application>Survex</Application> on a slow machine.</Para>

<Para><Application>Survex</Application> is capable of processing extremely complex caves very
quickly and has a very effective, real-time cave viewer which allows
you to rotate, zoom, and pan the cave using mouse or keyboard. We have
tested it extensively using <Acronym>CUCC</Acronym> and <Acronym>ARGE</Acronym>'s surveys of the caves
under the Loser Plateau in Austria (over 25,000 survey legs, and over
140km of underground survey data). This can all be processed in around
10 seconds on a low-end netbook.
Survex is also used by many other survey projects around the world,
including the 
<ulink url="http://www.oucc.org.uk/draenen/draenenmain.htm"
>Ogof Draenen</ulink> survey, the 
<ulink url="http://www.easegill.org.uk/">Easegill</ulink> resurvey project,
the <Acronym>OFD</Acronym> survey, the 
<!-- url="http://milos2.zoo.ox.ac.uk/~oucc/reports/surveys/surveys.htm" -->
<ulink url="http://www.oucc.org.uk/reports/surveys/surveys.htm"
><Acronym>OUCC</Acronym> Picos expeditions</ulink>, and the 
<ulink url="http://www.hongmeigui.net/">Hong Meigui China
expeditions</ulink>. <!-- FIXME more? --></Para>

<Para><Application>Survex</Application> is still actively being worked on.  Version 1.0 was
complete in some sense, but development continues - initially in reshaping
Survex into a more integrated GUI package.</Para>

<Para>We encourage feedback from users on important features or problems,
which will help to direct future development.  See the "Mailing List" section
of this manual for the best way to contact us.</Para>

</Sect2>

<!--
<Para>Because <Application>Survex</Application> is still being actively developed, this document
has an unfortunate tendency to lag slightly behind the capabilities of the
software. The latest version is now available on the web at <ulink
url="https://survex.com/">https://survex.com/</ulink> - check there for latest info.
</Para>
-->

<!--
<Sect2><Title>Other Documentation</Title>

<variablelist>
<varlistentry>
<term>NEWS or NEWS.txt</term>
<listitem><Para>a list of changes of interest to
<Application>Survex</Application> users, broken down by version number.  Consult this file
when upgrading to find out what has changed since the version you were
using previously.
</Para></listitem>
</varlistentry>

<varlistentry>
<term>ChangeLog or CHANGES.txt</term>
<listitem><Para>a much more detailed list of changes, aimed at developers
rather than end users.
</Para></listitem>
</varlistentry>

<varlistentry>
<term>BUGS or BUGS.txt</term>
<listitem><Para>a list of known bugs.
</Para></listitem>
</varlistentry>

<varlistentry>
<term>TODO or TODO.txt</term>
<listitem><Para>planned changes and enhancements.
</Para></listitem>
</varlistentry>

FIXME: merge INSTALL* into here, then process separately and textify
to produce INSTALL*

<varlistentry>
<term>INSTALL or INSTALL.txt</term>
<listitem><Para>instructions for installing <Application>Survex</Application>.  The
Microsoft Windows version comes packaged up with an installation wizard,
so this file doesn't exist there (you just run the package and follow
the on-screen instructions).
</Para></listitem>
</varlistentry>
</variablelist>

</Sect2>
-->

<Sect2><Title>About this Manual</Title>

<Para>
If there's a part of this manual you find hard to understand, please do
let us know.  We already know Survex well, so it can be hard for us
to spot areas where the manual doesn't given enough information, or
doesn't explain things clearly enough to follow when you don't know what's
going on.  It's helpful is you can suggest a better wording, but don't worry
if you can't, just explain the problem as precisely as you can.
</Para>

<Para>
The master version of this manual is an <acronym>SGML</acronym>
document written using the <ulink url="http://www.docbook.org/">docbook
<acronym>DTD</acronym></ulink>,
and automatically converted to a number of other formats.  If
you are going to send us <emphasis>major</emphasis> changes, it's much easier
to include them if you work from this master.  You can get it
from the source archive (docs/manual.sgml) or from <ulink
url="https://survex.com/docs.html">the Survex website</ulink>.
</Para>

<Sect3><Title>Terminology</Title>

<Para>Throughout this document we use British terminology for
surveying.</Para>

<variablelist>
<varlistentry>
<term>station</term>
<listitem><para>a point in the cave that you survey from and/or to
</para></listitem></varlistentry>

<varlistentry>
<term>leg</term>
<listitem><para>a line joining two stations
</para></listitem></varlistentry>

<varlistentry>
<term>survey</term>
<listitem><para>a group of legs surveyed on the same trip
</para></listitem></varlistentry>

</variablelist>

</Sect3>

</Sect2>

<!-- FIXME: Further sources of info: website, mailing lists, other docs -->

</Sect1>

<Sect1><Title>Getting Started</Title>
<?dbhtml filename="getstart.htm">

<Para>This section covers how to obtain the software, and how to unpack and
install it, and how to configure it.</Para>

<Sect2><Title>Obtaining <Application>Survex</Application></Title>

<Para>The latest version is available from the <Application>Survex</Application> website:
<ulink url="https://survex.com/">https://survex.com/</ulink>.  It is also
freely redistributable, so you welcome to get a copy from someone else
who has already downloaded it.</Para>

<Para>If you want some sample data to experiment with, you can download some
from the Survex website too:
<ulink url="https://survex.com/software/sample.tar.gz">https://survex.com/software/sample.tar.gz</ulink></Para>

</Sect2>

<Sect2><Title>Installing <Application>Survex</Application></Title>

<Para>The details of installation depend greatly on what platform you
are using, so there is a separate section below for each platform.</Para>

<Sect3><Title>Linux</Title>

<Para>
We supply pre-compiled versions for x86 Linux machines in RPM format
(suitable for Redhat, Mandrake, and some other distributions).
Survex Debian packages are available from Debian mirror sites in
the usual way.
</Para>

<Para>
You'll need root access to install these prebuilt packages.
If you don't have root access you will need to build from source
(see the next section).
</Para>

<!-- FIXME Add Gnome file association note for Linux/Unix
<Para>On Microsoft Windows, <Application>Survex</Application> installs with
suitable file associations so that you can drive it from the GUI.
On UNIX you need to drive <Application>Survex</Application> from a command-line
prompt (or set some a filemanager or graphics shell).
</Para>
-->

</Sect3>

<Sect3><Title>Other versions of UNIX</Title>

<Para>For other UNIX versions you'll need to get the source code
and compile it on your system.  Unpack the sources and read
the file called INSTALL in the top level for details about building
from source.
</Para>

</Sect3>

<Sect3><Title>Microsoft Windows</Title>

<Para>
This version comes packaged with an installation wizard.  Just
run the downloaded package and it will lead you through the
installation process.  If you want the file associations to be
set up for all user, run the installer as administrator, or as a
user with administrator rights.
</Para>

<Para>
The survey viewer that's part of <Application>Survex</Application> is called
aven, and uses OpenGL for 3d rendering.
</Para>

<Para>
If you find that 3D rendering is sometimes very slow (e.g. one user reported
very slow performance when running full screen, while running in a window
was fine) then try installing the OpenGL driver supplied by the manufacturer
of your graphics card rather than the driver Microsoft supply.
</Para>

<Para>
The installer creates a Survex group in the Programs sub-menu of the
Start menu containing the following items:
</Para>

<ItemizedList>

<ListItem><Para>Aven</Para></ListItem>

<ListItem><Para>Documentation</Para></ListItem>

<ListItem><Para>Uninstall Survex</Para></ListItem>

</ItemizedList>

<Para>
Icons are installed for <filename>.svx</filename>, <filename>.3d</filename>, <filename>.err</filename>, and <filename>.pos</filename> files, and also for
Compass Plot files (<filename>.plt</filename> and <filename>.plf</filename>)
(which Survex can read). <!-- FIXME XYZ -->
Double-clicking on a <filename>.svx</filename> file loads it for editing.  To process it to
produce a <filename>.3d</filename> file, right click and choose "Process" from the menu.
Double-clicking the resultant <filename>.3d</filename> file views it in aven.
All the <Application>Survex</Application> file types can be right clicked on to give a menu of
possible actions.  
</Para>

<VariableList>
<VarListEntry><Term><filename>.svx</filename></Term>
<ListItem>
  <VariableList>
  <VarListEntry><Term>Process</Term>
  <ListItem><Para>
  Process file with aven to produce <filename>.3d</filename> file (and <filename>.err</filename> file)
  </Para></ListItem>
  </VarListEntry>
  </VariableList>
</ListItem>
</VarListEntry>
    
<VarListEntry><Term><filename>.3d</filename></Term>
<ListItem>
  <VariableList>
  <VarListEntry><Term>Open</Term>
  <ListItem><Para>
  Load file into Aven
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Print</Term>
  <ListItem><Para>
  Send to the printer
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Extend</Term>
  <ListItem><Para>
  Produce extended elevation
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Convert to DXF</Term>
  <ListItem><Para>
  Convert to a DXF file (suitable for importing into many CAD packages)
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Convert for hand plotting</Term>
  <ListItem><Para>
  Produce a <filename>.pos</filename> file listing all the stations and their coordinates
  </Para></ListItem>
  </VarListEntry>
  </VariableList>
</ListItem>
</VarListEntry>

<VarListEntry><Term><filename>.err</filename></Term>
<ListItem>
  <VariableList>
  <VarListEntry><Term>Open</Term>
  <ListItem><Para>
  Load file into Notepad
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Sort by Error</Term>
  <ListItem><Para>
  Sort <filename>.err</filename> file by the error in each traverse
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Sort by Horizontal Error</Term>
  <ListItem><Para>
  Sort <filename>.err</filename> file by the horizontal error in each traverse
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Sort by Vertical Error</Term>
  <ListItem><Para>
  Sort <filename>.err</filename> file by the vertical error in each traverse
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Sort by Percentage Error</Term>
  <ListItem><Para>
  Sort <filename>.err</filename> file by the percentage error in each traverse
  </Para></ListItem>
  </VarListEntry>
  <VarListEntry><Term>Sort by Error per Leg</Term>
  <ListItem><Para>
  Sort <filename>.err</filename> file by the error per leg in each traverse
  </Para></ListItem>
  </VarListEntry>
  </VariableList>
</ListItem>
</VarListEntry>
</VariableList>

</Sect3>

</Sect2>

<Sect2><Title>Configuration</Title>

<Sect3><Title>Selecting Your Preferred Language</Title>

<Para>Survex has extensive internationalisation capabilities.  The
language used for messages from Survex and most of the library calls
it uses can be changed.  By default this is picked up from the
language the operating system is set to use (from "Regional Settings"
in Control Panel on Microsoft Windows, from the
<systemitem>LANG</systemitem> environment variable on UNIX
If no setting
is found, or <Application>Survex</Application> hasn't been translated into the
requested language, UK English is used.</Para>

<Para>
However you may want to override the language manually -
for example if Survex isn't available in your native language
you'll want to choose the supported language you understand best.
</Para>

<Para>
To do this, you set the
<systemitem>SURVEXLANG</systemitem> environment variable.  Here's a list
of the codes currently supported:</Para>

<informaltable frame="all">
<tgroup cols="2">
<thead>
<row><entry>Code</entry><entry>Language</entry></row>
</thead>
<tbody>
<row><entry>en</entry><entry>International English</entry></row>
<row><entry>en_US</entry><entry>US English</entry></row>
<row><entry>bg</entry><entry>Bulgarian</entry></row>
<row><entry>ca</entry><entry>Catalan</entry></row>
<row><entry>de</entry><entry>German</entry></row>
<row><entry>de_CH</entry><entry>Swiss German</entry></row>
<row><entry>el</entry><entry>Greek</entry></row>
<row><entry>es</entry><entry>Spanish</entry></row>
<row><entry>fr</entry><entry>French</entry></row>
<row><entry>hu</entry><entry>Hungarian</entry></row>
<row><entry>id</entry><entry>Indonesian</entry></row>
<row><entry>it</entry><entry>Italian</entry></row>
<row><entry>pl</entry><entry>Polish</entry></row>
<row><entry>pt</entry><entry>Portuguese</entry></row>
<row><entry>pt_BR</entry><entry>Brazillian Portuguese</entry></row>
<row><entry>ro</entry><entry>Romanian</entry></row>
<row><entry>ru</entry><entry>Russian</entry></row>
<row><entry>sk</entry><entry>Slovak</entry></row>
<row><entry>zh_CN</entry><entry>Chinese (Simplified)</entry></row>
</tbody>
</tgroup>
</informaltable>

<Para>Here are examples of how to set this environment variable to give
messages in French (language code fr):</Para>

<VariableList>
 <VarListEntry><Term>Microsoft Windows</Term>
   <ListItem><Para>
For MS Windows proceed as follows (this description was written from
MS Windows 2000, but it should be fairly similar in other versions): Open the
Start Menu, navigate to the Settings sub-menu, and
open Control Panel.  Open System (picture of a computer) and click on the
Advanced tab.  Choose `Environmental Variables', and create a new one: name
<systemitem>SURVEXLANG</systemitem>, value <systemitem>fr</systemitem>.
Click OK and the new value should be effective immediately.
   </Para></ListItem>
 </VarListEntry>
 <VarListEntry><Term>UNIX - csh/tcsh</Term>
   <ListItem><Para><userinput>setenv SURVEXLANG fr</userinput></Para></ListItem>
 </VarListEntry>
 <VarListEntry><Term>UNIX - sh/bash</Term>
   <ListItem><Para><userinput>SURVEXLANG=fr ; export SURVEXLANG</userinput></Para></ListItem>
 </VarListEntry>
</VariableList>

<Para>If <Application>Survex</Application> isn't available in your language, you could
help out by providing a translation.  The initial translation is
likely to be about a day's work; after that translations for
new or changed messages are occasionally required.  Contact us for details
if you're interested.</Para>

</Sect3>

</Sect2>

</Sect1>

<!-- FIXME

type in .svx file

run cavern (through aven)

run aven

how to print/export etc

-->

<!-- FIXME perhaps move this after data files section? -->
<Sect1><Title>Survex Programs</Title>
<?dbhtml filename="cmdline.htm">

<Sect2><Title>Standard Options</Title>

<Para>All <Application>Survex</Application> programs respond to the following command line options:
</Para>

<VariableList>

<VarListEntry><Term>--help</Term><listitem><Para>
display option summary and exit
</Para></listitem></VarListEntry>

<VarListEntry><Term>--version</Term><listitem><Para>
output version information and exit
</Para></listitem></VarListEntry>

</VariableList>

</Sect2>

<Sect2><Title>Short and Long Options</Title>

<Para>
Options have two forms: short (a dash followed by a single letter e.g.
<command>cavern -q</command>) and long (two dashes followed by one or more words e.g.
<command>cavern --quiet</command>).  The long form is generally easier to
remember, while the short form is quicker to type.  Options are often
available in both forms.
</Para>

<Note><Para>Command line options are case sensitive, so "-B" and "-b"
are different (this didn't used to be the case before Survex 0.90).  Case
sensitivity doubles the number of available short options (and is also the
norm on UNIX).
</Para></Note>
</Sect2>

<Sect2><Title>Filenames on the Command Line</Title>

<Para>Filenames with spaces can be processed (provided your operating system
supports them - UNIX does, and so do recent versions of Microsoft
Windows).  You need to enclose the filename in quotes like so:
<userinput>cavern "Spider Cave"</userinput>
</Para>

<Para>A file specified on the command line of any of the <Application>Survex</Application> suite
of programs will be looked for as specified.  If it is not found, then the
file is looked for with the appropriate extension appended.  So
<userinput>cavern survey</userinput> will look first for
<filename>survey</filename>, then for <filename>survey.svx</filename>.
</Para>

</Sect2>

<Sect2><title>Command Reference</title>

<refentry id="cavern">
<?dbhtml filename="cavern.htm">
&man.cavern;
</refentry>
<refentry id="aven">
<?dbhtml filename="aven.htm">
&man.aven;
</refentry>
<refentry id="x3dtopos">
<?dbhtml filename="3dtopos.htm">
&man.3dtopos;
</refentry>
<refentry id="cad3d">
<?dbhtml filename="cad3d.htm">
&man.cad3d;
</refentry>
<refentry id="diffpos">
<?dbhtml filename="diffpos.htm">
&man.diffpos;
</refentry>
<refentry id="extend">
<?dbhtml filename="extend.htm">
&man.extend;
</refentry>
<refentry id="sorterr">
<?dbhtml filename="sorterr.htm">
&man.sorterr;
</refentry>

</Sect2>

</Sect1>

<Sect1><Title><Application>Survex</Application> data files</Title>
<?dbhtml filename="datafile.htm">

<Para>Survey data is entered in the form of text files. You can use any
text editor you like for this, so long as it has the capability of
writing a plain ASCII text file. The data format is very flexible;
unlike some other cave surveying software, Survex does not require
survey legs to be rearranged to suit the computer, and the ordering 
of instrument readings on each line is fully specifiable.  So you can enter
your data much as it appears on the survey notes, which is important
in reducing the opportunities for transcription errors.
</Para>

<Para>
Also all the special characters are user-definable - for example,
the separators can be spaces and tabs, or commas (e.g. when exporting from a
spreadsheet), etc; the decimal point can be a slash (for clarity), a comma
(as used in continental Europe), or anything else you care to choose.
This flexibility
means that it should be possible to read in data from almost any sort of
survey data file without much work.
</Para>

<Para><Application>Survex</Application> places no restrictions on you in terms of the ordering
of survey legs. You can enter or process data in any order and <Application>Survex</Application> will
read it all in before determining how it is connected. You can also use the
hierarchical naming so that you do not need to worry about using the same
station name twice.
</Para>

<!-- FIXME don't encourage separate processing -->
<Para>The usual arrangement is to have one file which lists all the others
that are included (e.g., <filename>161.svx</filename>). Then
<command>cavern 161</command> will process all your data. To just process a
section use the filename for that section, e.g. <command>cavern dtime</command>
will process the dreamtime file/section of Kaninchenh&ouml;hle.  To
help you out, if all legs in a survey are connected to one another
but the survey has no fixed points, cavern
will 'invent' a fixed point and print a warning message to this
effect.
</Para>

<Para>
It is up to you what data you put in which files.  You
can have one file per trip, or per area of the cave, or just one
file for the whole cave if you like.
On a large survey project it makes sense to group related surveys in the
same file or directory.
</Para>
<!-- FIXME: wook sez:

 Point out in documentation that file structure and survey structure don't
 have to be the same.  And in particular that folder/directory names can be
 different.

Which is partly covered above, though the last bit isn't... 
-->

<!-- FIXME "Anatomy of a Survey" section -->
<Sect2><Title>Readings</Title>

<Para>Blank lines (i.e. lines consisting solely of BLANK characters)
are ignored. The last line in the file need not be terminated by
an end of line character. All fields on a line must be separated
by at least one BLANK character. An OMIT character
(default '-') indicates that a field is unused. If the field is
not optional, then an error is given.
</Para>

</Sect2>

<Sect2><Title>Survey Station Names</Title>

<Para><Application>Survex</Application> has a powerful system for naming stations.  It
uses a hierarchy of survey names, similar to the nested folders
your computer stores files in.
So point 6 in the entrance survey of Kaninchenh&ouml;hle
(cave number 161) is referred to as: 161.entrance.6
</Para>

<Para>This seems a natural way to refer to station names.  It also
means that it is very easy to include more levels, for example if you
want to plot all the caves in the area you just list them all in
another file, specifying a new prefix.  So to group 3 nearby caves
on the Loser Plateau you would use a file like
this:
</Para>

<programlisting>
*begin Loser
*include 161
*include 2YrGest
*include 145
*end Loser</programlisting>

<Para>
The entrance series point mentioned above would now be referred
to as: Loser.161.entrance.6
</Para>

<!--
<Para>This may seem a tad complex but is really very natural once you
get the hang of it.
</Para>
-->
<Para>You do not have to use this system at all, and can just give all
stations unique identifiers if you like:
</Para>

<Para>1, 2, 3, 4, 5, ... 1381, 1382
</Para>

<Para>or
</Para>

<Para>AA06, AA07, P34, ZZ6, etc.
</Para>

<!-- FIXME:
<Para>However you'll loose the ability to handle subsurveys if you do.
</Para>
-->

<Para>Station and survey names may contain any alphanumeric characters and
additionally any characters in NAMES (default `_' and `-'). Alphabetic
characters may be forced to upper or lower case by using the *case
command. Station names may be any length - if you want to only treat
the first few characters as significant you can get cavern to truncate
the names using the *truncate command.
</Para>

<Sect3><Title>Anonymous Stations</Title>

<Para>
Survex supports the concept of anonymous survey stations.  That is
survey stations without a name.  Each time an anonymous station name is
used it represents a different point.  Currently three types of anonymous
station are supported, referred to by one, two or three separator characters
- with the default separator of '.', that means '.', '..', and '...' are
anonymous stations.  Their meanings are:</Para>

<VariableList>
<VarListEntry><Term>Single separator ('.' by default)</Term>
<ListItem><Para>
An anonymous non-wall point at the end of an implicit splay.
</Para></ListItem></VarListEntry>

<VarListEntry><Term>Double separator ('..' by default)</Term>
<ListItem><Para>
An anoymous wall point at the end of an implicit splay.
</Para></ListItem></VarListEntry>

<VarListEntry><Term>Triple separator ('...' by default)</Term>
<ListItem><Para>
an anoymous point with no implicit flags on the leg (intended for cases like
a disto leg along a continuing passage).
</Para></ListItem></VarListEntry>
</VariableList>

<Para>
You can map '-' to '..' (for compatibility with data from pocket topo) using
the command:
</Para>

<programlisting>
*alias station - ..
</programlisting>

<Para>Support for anonymous stations and for '*alias station - ..' was added in
Survex 1.2.7.</Para>

</Sect3>

</Sect2>

<Sect2><Title>Numeric fields</Title>

<Para>[&lt;MINUS&gt;|&lt;PLUS&gt;] &lt;integer part&gt; [ &lt;DECIMAL&gt;
[ &lt;decimal fraction&gt; ] ]
</Para>

<Para>
or [&lt;MINUS&gt;|&lt;PLUS&gt;] &lt;DECIMAL&gt; &lt;dec fraction&gt;
</Para>

<Para><!-- FIXME: put informal description first -->
i.e. optional PLUS or MINUS sign in front, with
optional DECIMAL character (default '.'), which may be
embedded, leading or trailing. No spaces are allowed between the
various elements.
</Para>

<Para>
All of these are valid examples: +47, 23, -22, +4.5, 1.3, -0.7, +.15, .4,
-.05
</Para>

</Sect2>

<Sect2><Title>Accuracy</Title>

<Para>Accuracy assessments may be provided or defaulted for any survey
leg. These determine the distribution of loop closure errors over the
legs in the loop. See *SD for more information.
</Para>

</Sect2>

<!--
<Sect2><Title>Survey Coordinate Range</Title>

<Para>
If we store distances to nearest 10um (0.01mm) in 4 bytes, this
gives a range of ~20 km. This method is currently not used, but
has several advantages (data storage space [double uses 8 bytes
- with my C compiler], speed (unless your FP chip works in parallel
with your CPU [e.g. the new Acorn FPU for the ARM], and numerical
accuracy [compared to using floats at least]) and so may be adopted
in future). Nearest 0.1mm gives -200 km, which is enough for most
people, but may mean rounding errors become significant. 
</Para>

<Para>
I will have to do some sums...
</Para>

</Sect2>

-->

<Sect2><Title>Cavern Commands</Title>

<Para>Commands in <filename>.svx</filename> files are introduced by an asterisk
(by default - this can be changed using the <command>set</command> command).
</Para>

<Para>The commands are documented in a common format:
</Para>

<!-- FIXME: make this a RefGroup (or whatever that's called) of RefEntry-s? -->
<itemizedlist>
<listitem><para>Command Name</para></listitem>
<listitem><para>Syntax</para></listitem>
<listitem><para>Example</para></listitem>
<listitem><para>Validity</para></listitem>
<!-- FIXME
anywhere, in a block, at start of a block, after a begin (for *end)
-->
<listitem><para>Description</para></listitem>
<listitem><para>Caveats</para></listitem>
<listitem><para>See Also</para></listitem>
<!-- FIXME
"Usefulness" - or status maybe?
deprecated, esoteric (*set), useful, vital
-->
</itemizedlist>

<Sect3><Title>ALIAS</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*alias station &lt;alias&gt; [&lt;target&gt;]</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*begin parsons_nose
*alias station - ..
1 2 12.21 073 -12
2 -  4.33 011 +02
2 -  1.64 180 +03
2 3  6.77 098 -04
*end parsons_nose</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>*alias allows you to map a station name which appears in
the survey data to a different name internally.  At present, you can only
create an alias of '-' to '..', which is intended to support the pocket topo
style notation of '-' being a splay to an anonymous point on the cave wall.
And you can unalias '-' with '*alias station -'.
</Para>

<Para>
Aliases are scoped by *begin/*end blocks - when a *end is reached, the aliases
in force at the corresponding begin are restored.
</Para>

<Para>
*alias was added in Survex 1.2.7.
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin, *end</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>BEGIN</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*begin [&lt;survey&gt;]</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*begin littlebit
1 2 10.23 106 -02
2 3  1.56 092 +10
*end littlebit</programlisting>

<programlisting>
; length of leg across shaft estimated
*begin
*sd tape 2 metres
9 10 6.   031 -07
*end</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>*begin stores the current values of the current settings
such as instrument calibration, data format, and so on.
These stored values are restored after the corresponding *end.
If a survey name is given, this is used inside the *begin/*end block,
and the corresponding *end should have the same survey name.
*begin/*end blocks may be nested to indefinite depth.
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*end, *prefix</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>CALIBRATE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem>
<Para>*calibrate &lt;quantity list&gt; &lt;zero error&gt; [&lt;scale&gt;]
</Para>
<Para>*calibrate &lt;quantity list&gt; &lt;zero error&gt; &lt;units&gt; [&lt;scale&gt;]
</Para>
<Para>*calibrate default
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*calibrate tape +0.3
</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem>

<Para>
*calibrate is used to specify instrument calibrations, via a zero error
and a scale factor.  By default, the zero error is 0.0 and the scale
factor 1.0 for all quantities.
</Para>

<Para>
&lt;quantity&gt; is one of TAPE|COMPASS|CLINO|COUNTER|DEPTH|DECLINATION|X|Y|Z
</Para>

<Para>
Several quantities can be given in &lt;quantity list&gt; - the specified
calibration will be applied to each of them.
</Para>

<Para>
You need to be careful about the sign of the ZeroError.  Survex follows
the convention used with scientific instruments - the ZeroError is what
the instrument reads when measuring a reading which should be zero.  So
for example, if your tape measure has the end missing, and you are using the
30cm mark to take all measurements from, then a zero distance would be measured
as 30cm and you would correct this with:
</Para>

<programlisting>*CALIBRATE tape +0.3</programlisting>

<Para>If you tape was too long, starting at -20cm (it does happen!)
then you can correct it with:
</Para>

<programlisting>*CALIBRATE tape -0.2</programlisting>

<Para>Note: ZeroError is irrelevant for Topofil counters and depth
gauges since pairs of readings are subtracted.
</Para>

<Para>
In the first form in the synopsis above, the zero error is measured by the
instrument itself (e.g. reading off the number where a truncated tape now ends)
and any scale factor specified applies to it, like so:
</Para>

<Para>
Value = ( Reading - ZeroError ) * Scale    (Scale defaults to 1.0)
</Para>

<Para>
In the second form above (supported since Survex 1.2.21), the zero error has
been measured externally (e.g. measuring how much too long your tape is with
a ruler) - the units of the zero error are explicitly specified and any scale
factor isn't applied to it:
</Para>

<Para>
Value = ( Reading * Scale ) - ZeroError    (Scale defaults to 1.0)
</Para>

<Para>
If the scale factor is 1.0, then the two forms are equivalent, though they
still allow you to differentiate between how the zero error has been determined.
</Para>

<Para>
With older Survex versions, you would specify the magnetic declination
(difference between True North and Magnetic North) by using *calibrate
declination to set an explicit value (with no scale factor allowed).  Since
Survex 1.2.22, it's recommended to instead use the new *declination command
instead - see the documentation of that command for more details.
</Para>

</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*declination, *units</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>CASE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><para>*case preserve|toupper|tolower</para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*begin bobsbit
; Bob insists on using case sensitive station names
*case preserve
1 2   10.23 106 -02
2 2a   1.56 092 +10
2 2A   3.12 034 +02
2 3    8.64 239 -01
*end bobsbit</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>*case determines how the case of letters in survey names is
handled.  By default all names are forced to lower case (which gives a case
insensitive match, but you can tell cavern to force to upper case, or leave
the case as is (in which case '2a' and '2A' will be regarded as different).
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*truncate</Para></listitem>

</VarListEntry>

</VariableList>

<!-- FIXME - work this text in here or elsewhere

What I mean (though failed to express very well) is that a dataset without
this information isn't the same dataset (in general anyway).  For example:

A1 a2 10.32 140 -05
a2 a3  4.91 041 -01
a1 a3  7.01 206  02

is either a traverse of 3 legs or a (probably badly misclosed) loop.  If
these names are on the original survey notes, the surveyors ought to say
whether "A1" is the same as "a1" (although the usual case for using this
feature is probably for importing data from elsewhere).  Similarly for
truncation.  Whether a clino of +/-90 degrees (or +/-100 grad, etc) is
interpreted as a plumb is something that should have been noted in the cave
(unless it's implicit because it's standard practice for a survey project).

It's a similar issue to calibration data in many ways.  You can argue it's
not part of "the survey", but without it the survey won't be the same shape,
and it's not useful to process the same survey with different settings for
compass calibration or name case sensitivity.

>Clearly that is unhelpfully strict, but it is
>important to be semantically clear about what is 'data' and what is 'commands
>or meta-data' which describe what to do with/how to interpret that data.

Think of the lines starting with a "*" as "command or meta-data".

>The most-correct solution to this is (I believe) Martin Heller's idea about
>including 'rules' in the datastream, but that's too big a subject for right
>now.
>
>The reason '-C' was made into a command-line option, was that it made very
>little sense to change it part way though a dataset. What exactly happens if
>you suddenly tell cavern to become case-sensitive halfway through a run?

-C has always had 3 settings - "leave case alone", "force to lower", and
"force to upper".  It doesn't really mean "case sensitivity" but rather
something like "case processing".  So you can usefully change it during a
run.  So if my dataset treats "NoTableChamber" (so named because it was
lacking in furniture) as different from "NotableChamber" (which was notable
for other reasons) I can process it with a dataset from someone else which
needs to be treated as case insensitive like so:

*begin my_cave
*include my_dataset
*end my_cave

*equate my_cave.NoTableChamber.14 your_cave.linkpassage.13

*begin your_cave
*case tolower
*include your_dataset
*end your_cave

You may be thinking of -U<n>, which used to mean "only compare the first n
characters of station names", but that doesn't allow arbitrary datasets to
be processed together.

So we changed it to mean "truncate station names to n characters", and
allowed it to be changed at any point, rather than being set once for the
whole run.

-->

</Sect3>

<Sect3><Title>COPYRIGHT</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*copyright &lt;date&gt; &lt;text&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*begin littlebit
*copyright 1983 CUCC
1 2 10.23 106 -02
2 3  1.56 092 +10
*end littlebit</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Validity</Term>

<listitem><Para>valid at the start of a *begin/*end block.
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>*copyright allows the copyright information to be
stored in a way that can be automatically collated.
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>CS</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*cs [out] &lt;coordinate system&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*cs UTM60S
*fix beehive 313800 5427953 20</programlisting>
</Para>

<Para>
<programlisting>
; Output in the coordinate system used in the Totes Gebirge in Austria
*cs out custom "+proj=tmerc +lat_0=0 +lon_0=13d20 +k=1 +x_0=0 +y_0=-5200000 +ellps=bessel +towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232"</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>*cs allows the coordinate systems used for fixed points and for
processed survey data to be specified.
</Para>

<Para>
*cs was added in Survex 1.2.14, but handling of fixed points specified with
latitude and longitude didn't work until 1.2.21.  And *fix with standard
deviations specified also didn't work until 1.2.21.
</Para>

<Para>
The currently supported coordinate systems are:
</Para>

<Para>CUSTOM followed by a PROJ4 string (like in the example above).</Para>

<Para>EPSG: followed by a positive integer code.  EPSG codes cover most
coordinate systems in use, and PROJ supports many of these.  The website
<ulink url="https://epsg.io/">https://epsg.io/</ulink> is a useful resource for
finding the EPSG code you want.  Supported since Survex 1.2.15.</Para>

<Para>ESRI: followed by a positive integer code.  ESRI codes are used by
ArcGIS to specify coordinate systems (in a similar way to EPSG codes), and PROJ
supports many of them.  Supported since Survex 1.2.15.</Para>

<Para>EUR79Z30 for UTM zone 30, EUR79 datum.  Supported since Survex 1.2.15.
</Para>

<Para>IJTSK for the modified version of the Czechoslovak S-JTSK system where
the axes point East and North.  Supported since Survex 1.2.15.</Para>

<Para>IJTSK03 for a variant of IJTSK.  Supported since Survex 1.2.15.</Para>

<Para>JTSK for the Czechoslovak S-JTSK system.  The axes on this point West
and South, so it's not supported as an output coordinate system.
Supported since Survex 1.2.16.</Para>

<Para>JTSK03 for a variant of JTSK.  Supported since Survex 1.2.16.</Para>

<Para>LONG-LAT for longitude/latitude.  The WGS84 datum is assumed.
NB <command>*fix</command> expects the coordinates in the order x,y,z which
means longitude (i.e. E/W), then latitude (i.e. N/S), then altitude.
Supported since Survex 1.2.15.</Para>

<Para>OSGB: followed by a two letter code for the UK Ordnance Survey National
Grid.  The first letter should be 'H', 'N', 'O', 'S' or 'T'; the second any
letter except 'I'.  Supported since Survex 1.2.15.</Para>

<Para>S-MERC for the "Web Mercator" spherical mercator projection, used by
online map sites like OpenStreetMap, Google maps, Bing maps, etc.  Supported
since Survex 1.2.15.
</Para>

<Para>UTM followed by a zone number (1-60), optionally followed by "N" or "S"
(default is North).  The WGS84 datum is assumed.</Para>

<Para>
By default, Survex works in an unspecified coordinate system (and this was the
only option before *cs was added).  However, it's useful for coordinate system
which the processed survey data is in to be specified if you want to use the
processed data in ways which required knowing the coordinate system (such as
exporting a list of entrances for use in a GPS).  You can now do this by using
"*cs out".
</Para>

<Para>
It is also useful to be able to take coordinates for fixed points in whatever
coordinate system you receive them in and put them directly into Survex, rather
than having to convert with an external tool.  For example, you may have your
GPS set to show coordinates in UTM with the WGS84 datum, even though you want
the processed data to be in some local coordinate system.  And someone else
may provide GPS coordinates in yet another coordinate system.  You just need
to set the appropriate coordinate system with "*cs" before each group of "*fix"
commands in a particular coordinate system.
</Para>

<Para>
If you're going to make use of "*cs", then the coordinate system must be
specified for everything, so a coordinate system must be in effect for all
"*fix" commands, and you must set the output coordinate system before any
points are fixed.
</Para>

<Para>
Also, if "*cs" is in use, then you can't omit the coordinates in a "*fix"
command, and a fixed point won't be invented if none exists.
</Para>

<Para>
If you use "*cs out" more than once, the second and subsequent commands are
silently ignored - this makes it possible to combine two datasets with
different "*cs out" settings without having to modify either of them.
</Para>

<Para>
Something to be aware of with "*cs" is that altitudes are currently assumed to
be "height above the ellipsoid", whereas GPS units typically give you "height
above sea level", or more accurately "height above a particular geoid".  This
is something we're looking at how best to address, but you shouldn't need to
worry about it if your fixed points are in the same coordinate system as your
output, or if they all use the same ellipsoid.  For a more detailed discussion
of this, please see: http://expo.survex.com/handbook/survey/coord.htm
</Para>
</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*fix</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>
<Sect3><Title>DATA</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem>
<Para>*data &lt;style&gt; &lt;ordering&gt;</Para>
<Para>*data</Para>
</listitem>

<!-- BACKCOMPASS BACKCLINO -->
</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*data normal from to compass tape clino</programlisting>
</Para>

<Para>
<programlisting>
*data normal station ignoreall newline compass tape clino</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
&lt;style&gt; = DEFAULT|NORMAL|DIVING|CARTESIAN|TOPOFIL|CYLPOLAR|NOSURVEY|PASSAGE
</Para>

<Para>
&lt;ordering&gt; = ordered list of instruments - which are valid depends on the
style.
</Para>

<Para>
In Survex 1.0.2 and later, TOPOFIL is simply a synonym for NORMAL, left in to
allow older data to be processed without modification.  Use the name NORMAL
by preference.
</Para>

<Para>
There are two variants of each style - interleaved and non-interleaved.
Non-interleaved is "one line per leg", interleaved has a line for the data
shared between two legs (e.g. STATION=FROM/TO, DEPTH=FROMDEPTH/TODEPTH,
COUNT=FROMCOUNT/TOCOUNT).  Note that not all interleavable readings have to
be interleaved - for example:

<programlisting>
*data diving station newline fromdepth compass tape todepth</programlisting>

In addition, interleaved data can have a DIRECTION reading, which can be "F"
for a foresight or "B" for a backsight.
</Para>

<Para>
In NORMAL, DIVING, and CYLPOLAR data styles, TAPE may be replaced by
FROMCOUNT/TOCOUNT (or COUNT in interleaved data) to allow processing of surveys
performed with a Topofil instead of a tape.
</Para>

<Para>
In Survex 1.2.31 and later, you can use <command>*data</command> without any
arguments to keep the currently set data style, but resetting any state.  This
is useful when you're entering passage tubes with branches - see the description
of the "PASSAGE" style below.
</Para>

<VariableList>

<VarListEntry><Term>DEFAULT</Term>
<listitem><Para>Select the default data style and ordering (NORMAL style, ordering: from to tape compass clino).</Para></listitem>
</VarListEntry>

<VarListEntry><Term>NORMAL</Term>
<listitem><Para>The usual tape/compass/clino centreline survey.
For non-interleaved data the allowed readings are:
FROM TO TAPE COMPASS CLINO BACKCOMPASS BACKCLINO;
for interleaved data the allowed readings are:
STATION DIRECTION TAPE COMPASS CLINO BACKCOMPASS BACKCLINO.
The CLINO/BACKCLINO reading is not required - if it's not given, the vertical
standard deviation is taken to be proportional to the tape measurement.
Alternatively, individual clino readings can be given as OMIT (default "-")
which allows for data where only some clino readings are missing.
E.g.:

<programlisting>
*data normal from to compass clino tape
1 2 172 -03 12.61</programlisting>

<programlisting>
*data normal station newline direction tape compass clino
1
 F 12.61 172 -03
2</programlisting>

<programlisting>
*data normal from to compass clino fromcount tocount
1 2 172 -03 11532 11873</programlisting>

<programlisting>
*data normal station count newline direction compass clino
1 11532
 F 172 -03
2 11873</programlisting>
 
</Para></listitem>
</VarListEntry>

<VarListEntry><Term>DIVING</Term>
<listitem><Para>
An underwater survey where the vertical information is from a diver's depth
gauge.  This style can also be also used for an above-water survey where the
altitude is measured with an altimeter.  DEPTH is defined as the altitude (Z)
so increases upwards by default.  So for a diver's depth gauge, you'll need to
use *CALIBRATE with a negative scale factor (e.g. *calibrate depth 0 -1).
</Para>

<Para>For non-interleaved data the allowed readings are:
FROM TO TAPE COMPASS CLINO BACKCOMPASS BACKCLINO FROMDEPTH TODEPTH DEPTHCHANGE (the vertical
can be given as readings at each station, (FROMDEPTH/TODEPTH) or as a change
along the leg (DEPTHCHANGE)).</Para>

<Para>Survex 1.2.20 and later allow an optional CLINO and/or BACKCLINO reading
in DIVING style.  At present these extra readings are checked for syntactic
validity, but are otherwise ignored.  The intention is that a future version
will check them against the other readings to flag up likely blunders, and
average with the slope data from the depth gauge and tape reading.</Para>

<Para>For interleaved data the allowed readings are:
STATION DIRECTION TAPE COMPASS BACKCOMPASS DEPTH DEPTHCHANGE.
(the vertical change can be given as a reading at the station (DEPTH) or as a change along the leg (DEPTHCHANGE)).

<programlisting>
*data diving from to tape compass fromdepth todepth
1 2 14.7 250 -20.7 -22.4</programlisting>

<programlisting>
*data diving station depth newline tape compass
1 -20.7
 14.7 250
2 -22.4</programlisting>

<programlisting>
*data diving from to tape compass depthchange
1 2 14.7 250 -1.7</programlisting>
</Para>
</listitem>
</VarListEntry>

<VarListEntry><Term>CARTESIAN</Term>
<listitem><Para>
Cartesian data style allows you to specify the (x,y,z) changes between
stations.  It's useful for digitising surveys where the original survey
data has been lost and all that's available is a drawn up version.

<programlisting>
*data cartesian from to northing easting altitude
1 2 16.1 20.4 8.7</programlisting>

<programlisting>
*data cartesian station newline northing easting altitude
1
 16.1 20.4 8.7
2</programlisting>

<!--FIXME: dx dy dz-->
</Para>

<Note><Para>
Cartesian data are relative to <emphasis>true</emphasis> North not
<emphasis>magnetic</emphasis> North (i.e. they are unaffected by
<command>*calibrate declination</command>).
</Para></Note>
</listitem>
</VarListEntry>

<VarListEntry><Term>CYLPOLAR</Term>
<listitem><Para>
A CYLPOLAR style survey is very similar to a diving survey, except that the tape
is always measured horizontally rather than along the slope of the leg.

<programlisting>
*data cypolar from to tape compass fromdepth todepth
1 2 9.45 311 -13.3 -19.0</programlisting>

<programlisting>
*data cylpolar station depth newline tape compass
1 -13.3
 9.45 311
2 -19.0</programlisting>

<programlisting>
*data cylpolar from to tape compass depthchange
1 2 9.45 311 -5.7</programlisting>
</Para></listitem>
</VarListEntry>

<VarListEntry><Term>NOSURVEY</Term>
<listitem><Para>
A NOSURVEY survey doesn't have any measurements - it merely indicates that
there is line of sight between the pairs of stations.

<programlisting>
*data nosurvey from to
1 7
5 7
9 11</programlisting>

<programlisting>
*data nosurvey station
1
7
5

*data nosurvey station
9
11</programlisting>
</Para></listitem>
</VarListEntry>

<VarListEntry><Term>PASSAGE</Term>
<listitem><Para>
This survey style defines a 3D "tube" modelling a passage in the cave.
The tube uses the survey stations listed in the order listed.  It's
permitted to use survey stations which aren't directly linked by
the centre-line survey.  This can be useful - sometimes the centreline
will step sideways or up/down to allow a better sight for the next
leg and you can ignore the extra station.  You can also define tubes
along unsurveyed passages, akin to "nosurvey" legs in the centreline
data.</Para>

<Para>This means that you need to split off side passages into seperate
tubes, and hence separate sections of passage data, starting with
a new *data command.</Para>

<Para>
Simple example of how to use this data style (note the use of ignoreall
to allow a free-form text description to be given):

<programlisting>
*data passage station left right up down ignoreall
1  0.1 2.3 8.0 1.4  Sticking out point on left wall
2  0.0 1.9 9.0 0.5  Point on left wall
3  1.0 0.7 9.0 0.8  Highest point of boulder
</programlisting>

Each <command>*data passage</command> data block describes a single continuous
tube - to break a tube or to enter a side passage you need to have a second
block.  With Survex 1.2.30 and older, you had to repeat the entire
<command>*data passage</command> line to start a new tube, but in Survex 1.2.31
and later, you can just use <command>*data</command> without any arguments.
</Para>

<Para>
For example here the main passage is 1-2-3 and a side passage is 2-4:

<programlisting>
*data passage station left right up down ignoreall
1  0.1 2.3 8.0 1.4  Sticking out point on left wall
2  0.0 1.9 9.0 0.5  Point on left wall opposite side passage
3  1.0 0.7 9.0 0.8  Highest point of boulder
; If you're happy to require Survex 1.2.31 or later, you can just use
; "*data" here instead.
*data passage station left right up down ignoreall
2  0.3 0.2 9.0 0.5
4  0.0 0.5 6.5 1.5  Fossil on left wall
</programlisting>
</Para>
</listitem>
</VarListEntry>
</VariableList>

<Para>
IGNORE skips a field (it may be used any number of times),
and IGNOREALL may be used last to ignore the rest of the data line.
</Para>

<Para>
LENGTH is a synonym for TAPE; BEARING for COMPASS; GRADIENT for CLINO; COUNT for COUNTER.<!--FIXME : others?-->
</Para>

<Para>
The units of each quantity may be set with the UNITS command.
</Para>

<!-- FIXME: plumbed diving legs -->

<!--FIXME:
<Para>
Uses for CYLPOLAR:
Perhaps a Grade 3 survey, or when surveying with a level and stick (?)
[note - UBSS use it for the old County Clare data]
</Para>
-->

</listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>DATE</Title>
<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*date &lt;year&gt;[.&lt;month&gt;[.&lt;day&gt;]][-&lt;year&gt;[.&lt;month&gt;[.&lt;day&gt;]]]</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*date 2001</programlisting>

<programlisting>
*date 2000.10</programlisting>

<programlisting>
*date 1987.07.27</programlisting>

<programlisting>
*date 1985.08.12-1985.08.13</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Validity</Term>

<listitem><Para>valid at the start of a *begin/*end block.
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*date specifies the date that the survey was done.  A range of dates
can be specified (useful for overnight or multi-day surveying trips).
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin, *instrument, *team</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>DECLINATION</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem>
<Para>*declination &lt;auto&gt; &lt;x&gt; &lt;y&gt; &lt;z&gt;</Para>
<Para>*declination &lt;declination&gt; &lt;units&gt;</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem>

<Para>
The *declination command is the modern way to specify magnetic declinations in
Survex.  Prior to 1.2.22, *calibrate declination was used instead.  If you
use a mixture of *calibrate declination and *declination, they interact in
the natural way - whichever was set most recently is used for each compass
reading (taking into account survey scope).  We don't generally recommend
mixing the two, but it's useful to understand how they interact if you want to
combine datasets using the old and new commands, and perhaps if you have a
large existing dataset and want to migrate it without having to change
everything at once.
</Para>

<Para>
Magnetic declination is the difference between Magnetic North and True North.
It varies both with location and over time.  Compass bearings are measured
relative to Magnetic North - adding the magnetic declination gives bearings
relative to True North.
</Para>

<Para>
If you have specified the output coordinate system (using *cs out) then you can
use *declination auto (and we recommend that you do).  This is supported since
Survex 1.2.21 and automatically calculates magnetic declinations based on the
IGRF (International Geomagnetic Reference Field) model for the specified date
of each survey and at the specified representative location (given in the
current input coordinate system, as set with *cs).  Survex 1.2.27 and
later also automatically correct for grid convergence (the difference between
Grid North and True North) when *declination auto is in use, based on the same
specified representative location.
</Para>

<Para>
You might wonder why Survex needs a representative location instead of
calculating the magnetic declination and grid convergence for the actual
position of each survey station.  The reason is that we need to adjust the
compass bearings before we can solve the network to find survey station
locations.  Both magnetic declination and grid convergence don't generally vary
significantly over the area of a typical cave system - if you are mapping a
very large cave system, or caves over a wide area, or are working close to a
magnetic pole or where the output coordinate system is rather distorted, then
you can specify *declination auto several times with different locations - the
one currently in effect is used for each survey leg.
</Para>

<Para>
Generally it's best to specify a suitable output coordinate system, and use
*declination auto so Survex corrects for magnetic declination and grid
convergence for you.  Then Aven knows how to translate coordinates to allow
export to formats such as GPX and KML, and to overlay terrain data.
</Para>

<Para>
If you don't specify an output coordinate system, but fix one or more points
then Survex works implicitly in the coordinate system your fixed points were
specified in.  This mode of operation is provided for compatibility with
datasets from before support for explicit coordinate systems was added to
Survex - it's much better to specify the output coordinate system as above.
But if you have a survey of a cave which isn't connected to any known fixed
points then you'll need to handle it this way, either fixing an entrance
to some arbitrary coordinates (probably (0,0,0)) or letting Survex pick a
station as the origin.  If the survey was all done in a short enough period
of time that the magnetic declination won't have changed significantly, you
can just ignore it and Grid North in the implicit coordinate system will be
Magnetic North at the time of the survey.  If you want to correct for magnetic
declination, you can't use *declination auto because the IGRF model needs the
real world coordinates, but you can specify literal declination values for each
survey using *declination &lt;declination&gt; &lt;units&gt;.  Then Grid North
in the implicit coordinate system is True North.
</Para>

<Para>
Note that the value specified uses the conventional sign for magnetic
declination, unlike the old *calibrate declination which needed a value with
the opposite sign (because *calibrate specifies a zero error), so take care
when updating old data, or if you're used to the semantics of *calibrate
declination.
</Para>

</listitem>

</VarListEntry>

<VarListEntry><Term>See Also</Term>

<listitem><Para>*calibrate</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>DEFAULT</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*default &lt;settings list&gt;|all</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
The valid settings are CALIBRATE, DATA, and UNITS.
</Para>

<Para>
*default restores defaults for given settings.  This command is deprecated -
you should instead use: *calibrate default, *data default, *units default.
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>See Also</Term>

<listitem><Para>*calibrate, *data, *units</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>END</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*end [&lt;survey&gt;]</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Validity</Term>

<listitem><Para>valid for closing a block started by *begin in the same file.
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
Closes a block started by *begin.
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>ENTRANCE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*entrance &lt;station&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*entrance P163</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*entrance sets the <emphasis>entrance</emphasis> flag for a station.
This information is used by aven to allow entrances to be highlighted.
</Para>

<!-- FIXME:
(could be inferred from surface/ug join, but better to specify because
of caves with no surf svy (or no underground survey) 
and also situations in which multiple surveys leave through an entrance)
-->
</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<!-- <VarListEntry><Term>See Also</Term>

<listitem><Para></Para></listitem>

</VarListEntry>
-->

</VariableList>

</Sect3>

<Sect3><Title>EQUATE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*equate &lt;station&gt; &lt;station&gt;...</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*equate chosspot.1 triassic.27</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*equate specifies that the station names in the list refer to the
same physical survey station. An error is given if there is only one station
listed.
</Para>

<!-- FIXME:
<Para>
I think this is preferable to using:
</Para>

<programlisting> a b 0.00   0   0</programlisting>

<Para>
as EQUATE does not add in an extra position error. It is also clearer than
substituting in the original name wherever passages are linked. If you
disagree, you can always use one of the other methods!
</Para>
-->
</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*infer equates</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>EXPORT</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*export &lt;station&gt;...</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<!-- FIXME better example -->
<listitem>
<Para>
<programlisting>
*export 1 6 17</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Validity</Term>

<listitem><Para>valid at the start of a *begin/*end block.
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*export marks the stations named as referable to from the enclosing
survey.  To be able to refer to a station from a survey several levels
above, it must be exported from each enclosing survey.
</Para>

<!-- FIXME:
<Para>
I think this is preferable to using:
</Para>

<programlisting> a b 0.00   0   0</programlisting>

<Para>
as EQUATE does not add in an extra position error. It is also clearer than
substituting in the original name wherever passages are linked. If you
disagree, you can always use one of the other methods!
</Para>
-->
</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin, *infer exports</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>FIX</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*fix &lt;station&gt; [reference]
 [ &lt;x&gt; &lt;y&gt; &lt;z&gt;
   [ &lt;x std err&gt; &lt;y std err&gt; &lt;z std err&gt;
     [ &lt;cov(x,y)&gt; &lt;cov(y,z)&gt; &lt;cov(z,x)&gt; ] ] ]
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*fix entrance.0 32768 86723 1760</programlisting>

<programlisting>
*fix KT114_96 reference 36670.37 83317.43 1903.97</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem>
<Para>
*fix fixes the position of &lt;station&gt; at the given coordinates.
If you haven't specified the coordinate system with "*cs", you can
omit the position and it will default to (0,0,0).  The standard errors default
to zero (fix station exactly).  cavern will give an error if you attempt to fix
the same survey station twice at different coordinates, or a warning if you fix
it twice with matching coordinates.
</Para>

<Para>
You can also specify just one standard error (in which case it is assumed
equal in X, Y, and Z) or two (in which case the first is taken as the
standard error in X and Y, and the second as the standard error in Z).
</Para>

<Para>
If you have covariances for the fix, you can also specify these - the
order is cov(x,y) cov(y,z) cov(z,x). 
</Para>

<Para>
You can fix as many stations as you like - just use a *fix command for each
one.  Cavern will check that all stations are connected to
at least one fixed point so that co-ordinates can be calculated for all
stations.
</Para>

<Para>
By default cavern will warn about stations which have been FIX-ed but
not used otherwise, as this might be due to a typo in the station
name.  This is unhelpful if you want to include a standard file of benchmarks,
some of which won't be used.  In this sort of situation, specify "REFERENCE"
after the station name in the FIX command to suppress this warning for a
particular station.
</Para>

<Note><Para>
X is Easting, Y is Northing, and Z is altitude.  This convention was chosen
since on a map, the horizontal (X) axis is usually East, and the vertical
axis (Y) North.  The choice of altitude (rather than depth) for Z is taken
from surface maps, and makes for less confusion when dealing with cave
systems with more than one entrance.  It also gives a right-handed
set of axes.
</Para></Note>

</listitem>
</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<!-- <VarListEntry><Term>See Also</Term>

<listitem><Para></Para></listitem>

</VarListEntry>
-->

</VariableList>

</Sect3>

<!--
<Sect3><Title></Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Caveats </Term> </VarListEntry>

<VarListEntry><Term>See Also</Term>

<listitem><Para></Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>
-->

<Sect3><Title>FLAGS</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*flags &lt;flags&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*flags duplicate not surface</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*flags updates the current flag settings.
Flags not mentioned retain their previous state.  Valid flags
are DUPLICATE, SPLAY, and SURFACE, and a flag may be preceded with NOT to
turn it off.
</Para>

<Para>
Survey legs marked SURFACE are hidden from plots by default, and not
included in cave survey length calculations.  Survey legs marked as
DUPLICATE or SPLAY are also not included in cave survey length
calculations; legs marked SPLAY are ignored by the extend program.
DUPLICATE is intended for the case when if you have two different
surveys along the same section of passage (for example to tie two
surveys into a permanent survey station); SPLAY is intended for 
cases such as radial legs in a large chamber.
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>INCLUDE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*include &lt;filename&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*include mission</programlisting>

<programlisting>
*include "the pits"</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*include processes &lt;filename&gt; as if it were inserted at this
place in the current file. (i.e. The current settings are carried
into &lt;filename&gt;, and any alterations to settings in &lt;filename&gt;
will be carried back again).  There's one exception to this (for
obscure historical reasons) which is that the survey prefix is
restored upon return to the original file.  Since *begin and *end
nesting cannot cross files, this can only make a difference if you
use the deprecated *prefix command.
</Para>

<Para>If &lt;filename&gt; contains spaces, it must be enclosed in quotes.
</Para>

<Para>An included file which does not have a complete path
is resolved relative to the directory which the parent file is in
(just as relative HTML links do).  Cavern will try adding a <filename>.svx</filename>
extension, and will also try translating "\" to "/".
And as a last
resort, it will try a lower case version of the filename (so if you
use Unix and someone sends you a DOS/Windows dataset with mismatched
case, unzip it with "unzip -L" and UNIX cavern will process it).
</Para>

<Para>
The depth to which you can nest
include files may be limited by the operating system
you use.  Usually the limit is fairly high (>30), but if you want to be able to
process your dataset with <Application>Survex</Application> on any supported platform, it
would be prudent not to go overboard with nested include files.
</Para>
</listitem>
</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>INFER</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem>
<Para>*infer plumbs on|off</Para>

<Para>*infer equates on|off</Para>

<Para>*infer exports on|off</Para>
</listitem>

</VarListEntry>

<!--
<VarListEntry><Term>Example</Term>

<listitem>
<programlisting>
</programlisting>

</listitem>

</VarListEntry>
-->

<VarListEntry><Term>Description</Term>

<listitem>
<Para>"*infer plumbs on" tells cavern to interpret gradients of +/- 90
degrees as UP/DOWN (so it
will not apply the clino correction to them). This is useful when
the data has not been converted to have UP and DOWN in it.
</Para>

<para>"*infer equates on" tells cavern to interpret a leg with
a tape reading of zero as a *equate.  this prevents tape corrections
being applied to them.
</para>

<para>"*infer exports on" is necessary when you have a dataset which is
partly annotated with *export.  It tells cavern not to complain about
missing *export commands in part of the dataset.  Also stations which
were used to join surveys are marked as exported in the 3d file.
</para>
</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<!--
<VarListEntry><Term>See Also</Term>

<listitem><Para>*end, *prefix</Para></listitem>

</VarListEntry>
-->

</VariableList>

</Sect3>

<Sect3><Title>INSTRUMENT</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*instrument &lt;instrument&gt; &lt;identifier&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*instrument compass "CUCC 2"
*instrument clino "CUCC 2"
*instrument tape "CUCC Fisco Ranger open reel"</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Validity</Term>

<listitem><Para>valid at the start of a *begin/*end block.
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*instrument specifies the particular instruments used to perform a
survey.
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin, *date, *team</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>PREFIX</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*prefix &lt;survey&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*prefix flapjack</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*prefix sets the current survey.
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Caveats </Term>

<listitem><Para>*prefix is deprecated - you should use *begin and *end
instead.</Para></listitem>

</VarListEntry>

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin, *end</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>REF</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*ref &lt;string&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*ref "survey folder 2007#12"
</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Validity</Term>

<listitem><Para>valid at the start of a *begin/*end block.
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*ref allows you to specify a reference.  If the reference contains spaces, you
must enclose it in double quotes.  Survex doesn't try to interpret the
reference in any way, so it's up to you how you use it - for example it could
specify where the original survey notes can be found.
</Para>

<Para>
*ref was added in Survex 1.2.23.
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin, *date, *instrument, *team</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>REQUIRE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*require &lt;version&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*require 0.98</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*require checks that the version of cavern in use is at least
&lt;version&gt; and stops with an error if not.
So if your dataset requires a feature
introduced in a particular version, you can add a *require command and
users will know what version they need to upgrade to, rather than
getting an error message and having to guess what the real problem is.
</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>SD</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*sd &lt;quantity list&gt; &lt;standard deviation&gt;
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*sd tape 0.15 metres</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*sd sets the standard deviation of a measurement.
</Para>

<Para>
&lt;quantity&gt; is one of (each group gives alternative names for the same
quantity):
</Para>

<ItemizedList>
    <listitem><para>TAPE, LENGTH</para></listitem>
    <listitem><para>BACKTAPE, BACKLENGTH (added in Survex 1.2.25)</para></listitem>
    <listitem><para>COMPASS, BEARING</para></listitem>
    <listitem><para>BACKCOMPASS, BACKBEARING</para></listitem>
    <listitem><para>CLINO, GRADIENT</para></listitem>
    <listitem><para>BACKCLINO, BACKGRADIENT</para></listitem>
    <listitem><para>COUNTER, COUNT</para></listitem>
    <listitem><para>DEPTH</para></listitem>
    <listitem><para>DECLINATION</para></listitem>
    <listitem><para>DX, EASTING</para></listitem>
    <listitem><para>DY, NORTHING</para></listitem>
    <listitem><para>DZ, ALTITUDE</para></listitem>
    <listitem><para>LEFT</para></listitem>
    <listitem><para>RIGHT</para></listitem>
    <listitem><para>UP, CEILING</para></listitem>
    <listitem><para>DOWN, FLOOR</para></listitem>
    <listitem><para>LEVEL</para></listitem>
    <listitem><para>PLUMB</para></listitem>
    <listitem><para>POSITION</para></listitem>
</ItemizedList>

<Para>
&lt;standard deviation&gt; must include units and thus is typically
"0.05 metres", or "0.02 degrees". See *units below for full list
of valid units.
</Para>

<!-- FIXME mention central limit theorem -->
<Para>
To utilise this command fully you need to understand what a
<emphasis>standard deviation</emphasis> is.
It gives a value to the 'spread' of the errors
in a measurement. Assuming that these are normally distributed
we can say that 95.44% of the actual lengths will fall within two
standard deviations of the measured length. i.e. a tape SD of
0.25 metres means that the actual length of a tape measurement
is within + or - 0.5 metres of the recorded value 95.44% of the time.
So if the measurement is 7.34m then the actual length is very
likely to be between 6.84m and 7.84m. This example corresponds
to BCRA grade 3. Note that this is just one interpretation of
the BCRA standard, taking the permitted error values as 2SD 95.44%
confidence limits. If you want to take the readings as being some
other limit (e.g. 1SD = 68.26%) then you will need to change the BCRA3
and BCRA5 files accordingly. This issue is explored in more
detail in various surveying articles.
<!--
2.565 sd 99%
2.5   sd 98.76%
2     sd 95.44%
1     sd 68.26%
.97   sd 66.67%
1.15  sd 75%
-->
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>See Also</Term>

<listitem><Para>*units</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>SET</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*set &lt;item&gt; &lt;character list&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*set blank x09x20
*set decimal ,</programlisting>

Note that you need to eliminate comma from being a blank before setting it as
a decimal - otherwise the comma in "*set decimal ," is parsed as a blank, and
you set decimal to not have any characters representing it.
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*set sets the specified &lt;item&gt; to the character or characters
given in &lt;character list&gt;. The example sets the decimal
separator to be a comma.
</Para>

<Para>
xAB means the character with hex value AB. Eg x20 is a space.
</Para>

<Para>
The complete list of items that can be set, the defaults (in
brackets), and the meaning of the item, is:
</Para>

<ItemizedList>

<ListItem><Para>
BLANK (x09x20,) Separates fields
</Para></ListItem>

<ListItem><Para>
COMMENT (;) Introduces comments
</Para></ListItem>

<ListItem><Para>
DECIMAL (.) Decimal point character 
</Para></ListItem>

<ListItem><Para>
EOL (x0Ax0D) End of line character
</Para></ListItem>

<ListItem><Para>
KEYWORD (*) Introduces keywords
</Para></ListItem>

<ListItem><Para>
MINUS (-) Indicates negative number
</Para></ListItem>

<ListItem><Para>
NAMES (_-) Non-alphanumeric chars permitted in station
names (letters and numbers are always permitted).
</Para></ListItem>

<ListItem><Para>
OMIT (-) Contents of field omitted (e.g. in plumbed legs)
</Para></ListItem>

<ListItem><Para>
PLUS (+) Indicates positive number 
</Para></ListItem>

<ListItem><Para>
ROOT (\) Prefix in force at start of current file (use of ROOT is deprecated)
</Para></ListItem>

<ListItem><Para>
SEPARATOR (.) Level separator in prefix hierarchy
</Para></ListItem>

<!-- FIXME OPEN ({) and CLOSE (}) -->
</ItemizedList>

<Para>
The special characters may not be alphanumeric.
</Para>

</listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>SOLVE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*solve</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*include 1997data
*solve
*include 1998data
</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
Distributes misclosures around any loops in the survey and fixes
the positions of all existing stations.  This command is intended
for situations where you have some new surveys adding extensions
to an already drawn-up survey which you wish to avoid completely
redrawing. You can read in the old data, use *SOLVE to fix it, and then
read in the new data.  Then old stations will be in the same
positions as they are in the existing drawn up survey, even if new loops
have been formed by the extensions.
</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>TEAM</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*team &lt;person&gt; &lt;role&gt;...</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*team "Nick Proctor" compass clino tape
*team "Anthony Day" notes pictures tape
</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Validity</Term>

<listitem><Para>valid at the start of a *begin/*end block.
</Para></listitem>
<!-- FIXME valid roles are? -->

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
*team specifies the people involved in a survey and what role they
filled during that trip.
</Para></listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*begin, *date, *instrument</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>TITLE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*title &lt;title&gt;</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<programlisting>
*title Dreamtime</programlisting>

<programlisting>
*title "Mission Impossible"</programlisting>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>*title allows you to set the descriptive title for a survey.
If the title contains spaces, you need to enclose it in quotes ("").
If there is no *title command, the title defaults to the survey name
given in the *begin command.
</Para>
</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<!--
<VarListEntry><Term>See Also</Term>

<listitem><Para>*end, *prefix</Para></listitem>

</VarListEntry>
-->

</VariableList>

</Sect3>

<Sect3><Title>TRUNCATE</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>*truncate &lt;length&gt;|off</Para></listitem>

</VarListEntry>

<!-- FIXME:
<VarListEntry><Term>Example</Term>

<listitem>
<programlisting>
</programlisting>

</listitem>

</VarListEntry>
-->

<VarListEntry><Term>Description</Term>

<listitem><Para>Station names may be of any length in <Application>Survex</Application>, but some
other (mostly older) cave surveying software only regard the first few
characters of a name as significant (e.g. "entran" and "entrance"
might be treated as the same).  To facilitate using data imported from
such a package <Application>Survex</Application> allows you to truncate names to whatever
length you want (but by default truncation is off).
</Para>

<Para>Figures for the number of characters which are significant in various
software packages: Compass currently has a limit of 12,
CMAP has a limit of 6,
Smaps 4 had a limit of 8,
<!-- FIXME any limits for other software, winkarst for example? -->
Surveyor87/8 used 8.
<Application>Survex</Application> itself used 8 per prefix
level up to version 0.41, and 12 per prefix level up to 0.73 (more recent
versions removed this rather archaic restriction).
</Para>
</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*case</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

<Sect3><Title>UNITS</Title>

<VariableList>

<VarListEntry><Term>Syntax</Term>

<listitem><Para>
*units &lt;quantity list&gt; [&lt;factor&gt;] &lt;unit&gt;
</Para>
<Para>
*units default
</Para></listitem>

</VarListEntry>

<VarListEntry><Term>Example</Term>

<listitem>
<Para>
<programlisting>
*units tape metres</programlisting>

<programlisting>
*units compass backcompass clino backclino grads</programlisting>

<programlisting>
*units dx dy dz 1000 metres ; data given as kilometres</programlisting>

<programlisting>
*units left right up down feet</programlisting>
</Para>
</listitem>

</VarListEntry>

<VarListEntry><Term>Description</Term>

<listitem><Para>
&lt;quantity&gt; is one of the following (grouped entries are just alternative names for the same thing):
TAPE/LENGTH, BACKTAPE/BACKLENGTH (added in Survex 1.2.25), COMPASS/BEARING, BACKCOMPASS/BACKBEARING, CLINO/GRADIENT, BACKCLINO/BACKGRADIENT, COUNTER/COUNT, DEPTH, DECLINATION, DX/EASTING, DY/NORTHING, DZ/ALTITUDE, LEFT, RIGHT, UP/CEILING, DOWN/FLOOR
</Para>

<Para>Changes current units of all the quantities listed to [&lt;factor&gt;]
&lt;unit&gt;. Note that quantities can be expressed either as
the instrument (e.g. COMPASS) or the measurement (e.g. BEARING).
</Para>

<Para>&lt;factor&gt; allows you to easy specify situations such as measuring
distance with a diving line knotted every 10cm (*units distance 0.1 metres).
If &lt;factor&gt; is omitted it defaults to 1.0.  If specified, it must be
non-zero.
</Para>

<Para>Valid units for listed quantities are:
</Para>

<Para>TAPE/LENGTH, BACKTAPE/BACKLENGTH, COUNTER/COUNT, DEPTH, DX/EASTING, DY/NORTHING, DZ/ALTITUDE
in YARDS|FEET|METRIC|METRES|METERS (default: METRES)
</Para>

<Para>CLINO/GRADIENT, BACKCLINO/BACKGRADIENT
in DEGS|DEGREES|GRADS|MILS|MINUTES|PERCENT|PERCENTAGE (default: DEGREES)
</Para>

<Para>COMPASS/BEARING, BACKCOMPASS/BACKBEARING, DECLINATION
in DEGS|DEGREES|GRADS|MILS|MINUTES (default: DEGREES)
</Para>

<Para>(360 degrees = 400 grads (also known as Mils))
</Para>
</listitem>

</VarListEntry>

<!-- <VarListEntry><Term>Caveats </Term> </VarListEntry> -->

<VarListEntry><Term>See Also</Term>

<listitem><Para>*calibrate</Para></listitem>

</VarListEntry>

</VariableList>

</Sect3>

</Sect2>

</Sect1>

<!-- FIXME rename to "Cookbook"? -->
<Sect1><Title>Contents of <filename>.svx</filename> files: How do I?</Title>
<?dbhtml filename="svxhowto.htm">

<Para>
Here is some example <Application>Survex</Application> data (a very small cave numbered 1623/163):
</Para>

<programlisting>
2 1 26.60 222  17.5
2 3 10.85 014   7
2 4  7.89 254 -11
4 5  2.98  - DOWN
5 6  9.29 271 -28.5</programlisting>

<Para>
You can vary the data ordering.  The default is:
</Para>

<Para>
from-station to-station tape compass clino
</Para>

<Para>
This data demonstrates a number of useful features of <Application>Survex</Application>:
</Para>

<Para>
Legs can be measured either way round, which allows the use of
techniques like "leap-frogging" (which is where legs
alternate forwards and backwards).
</Para>

<Para>
Also notice that there is a spur in the survey (2 to 3).  You
do not need to specify this specially.
</Para>

<Para>
<Application>Survex</Application> places few restrictions on station naming (see "Survey
Station Names" in the previous section), so you can number the stations
as they were in the original survey notes.  Although not apparent from
this example, there is no requirement for each leg to connect to an
existing station.  <Application>Survex</Application> can accept data in any order, and will
check for connectedness once all the data has been read in.
</Para>

<Para>
Each survey is also likely to have other information associated
with it, such as instrument calibrations, etc.  This has been
omitted from this example to keep things simple.
</Para>

<Para>
Most caves will take more than just one survey trip to map.  Commonly
the numbering in each survey will begin at 1, so we need to be
able to tell apart stations with the same number in different
surveys.
</Para>

<Para>
To accomplish this, <Application>Survex</Application> has a very flexible system of hierarchical
prefixes.  All you need do is give each survey a unique name or
number, and enter the data like so:
</Para>

<programlisting>
*begin 163
*export 1
2 1 26.60 222  17.5
2 3 10.85 014   7
2 4  7.89 254 -11
4 5  2.98  - DOWN
5 6  9.29 271 -28.5
*end 163</programlisting>

<Para><Application>Survex</Application> will name the stations by attaching the current prefix.
In this case, the stations will be named 163.1, 163.2, etc.
</Para>

<Para>We have a convention with the CUCC Austria data that the entrance survey
station of a cave is named P&lt;cave number&gt;, P163 in this case. We
can accomplish this like so:
</Para>

<programlisting>
*equate P163 163.1
*entrance P163
*begin 163
*export 1
2 1 26.60 222  17.5
2 3 10.85 014   7
2 4  7.89 254 -11
4 5  2.98  - DOWN
5 6  9.29 271 -28.5
*end 163</programlisting>

<Sect2><Title>Specify surface survey data</Title>

<Para>
Say you have 2 underground surveys and 2 surface ones with 2 fixed reference
points.  You want to mark the surface surveys so that their length isn't
included in length statistics, and so that Aven knows to display them
differently.  To do this you mark surface data with the "surface" flag
- this is set with "*flags surface" like so:
</Para>

<programlisting>
; fixed reference points
*fix fix_a 12345 56789 1234
*fix fix_b 23456 67890 1111                                                     
                                                                                
; surface data (enclosed in *begin ... *end to stop the *flags command
; from "leaking" out)
*begin
*flags surface
*include surface1
*include surface2
*end                                                                            
                                                                                
; underground data
*include cave1
*include cave2</programlisting>

<Para>
You might also have a survey which starts on the surface and heads into a
cave.  This can be easily handled too - here's an example which goes in
one entrance, through the cave, and out of another entrance:
</Para>

<programlisting>
*begin BtoC
*title "161b to 161c"
*date 1990.08.06 ; trip 1990-161c-3 in 1990 logbook

*begin
*flags surface
02    01      3.09   249    -08.5
02    03      4.13   252.5  -26
*end

04    03      6.00   020    +37
04    05      3.07   329    -31
06    05      2.67   203    -40.5
06    07      2.20   014    +04
07    08      2.98   032    +04
08    09      2.73   063.5  +21
09    10     12.35   059    +15

*begin
*flags surface
11    10      4.20   221.5  -11.5
11    12      5.05   215    +03.5
11    13      6.14   205    +12.5
13    14     15.40   221    -14
*end

*end BtoC</programlisting>

<Para>
Note that to avoid needless complication, Survex regards each leg as
being either "surface" or "not surface" - if a leg spans the boundary you'll
have to call it one or the other.  It's good surveying practice to
deliberately put a station at the surface/underground interface
(typically the highest closed contour or drip line) so this generally
isn't an onerous restriction.
</Para>

</Sect2>

<Sect2><Title>Specify the ordering and type of data</Title>

<Para>The *DATA command is used to specify the data style, and the
order in which the readings are given.</Para>

</Sect2>

<Sect2><Title>Deal with Plumbs or Legs Across Static Water</Title>

<!-- FIXME
<Para>
They can be given
as +90, or -90, but as they are not usually measured with the
clino, but with a plumb of some sort, then it is useful to distinguish
them in this way so that any clino adjustment is not applied to
these values.
</Para>

FIXME: paste in section from mail to list

<Para>
Note that a similar effect can be achieved by using the "*infer plumbs" command
to stop clino corrections being applied to -90 and +90 clino readings.
</Para>
-->

<Para>
Plumbed legs should be given using 'UP' or 'DOWN' in place of the
clino reading and a dash (or a different specified 'OMIT' character)
in place of the compass reading.  This distinguishes
them from legs measured with a compass and clino.  Here's an example:
</Para>

<programlisting>
1 2 21.54 - UP
3 2 7.36 017 +17
3 4 1.62 091 +08
5 4 10.38 - DOWN</programlisting>

<Para>
U/D or +V/-V may be used instead of UP/DOWN; the check is not case
sensitive.
</Para>

<Para>
Legs surveyed across the surface of a static body of water where no
clino reading is taken (since the surface of the water can be assumed
to be flat) can be indicated by using LEVEL in place of a clino reading.
This prevents the clino correction being applied.  Here's an example:
</Para>

<programlisting>
1 2 11.37 190 -12
3 2  7.36 017 LEVEL
3 4  1.62 091 LEVEL</programlisting>

</Sect2>

<Sect2><Title>Specify a BCRA grade</Title>

<Para>The *SD command can be used to specify the standard deviations of the
various measurements (tape, compass, clino, etc).  Examples files are
supplied which define BCRA Grade 3 and BCRA Grade 5 using a number of *sd
commands. You can use these by simply including them at the relevant point,
as follows:
</Para>

<programlisting>
*begin somewhere
; This survey is only grade 3
*include grade3
2 1 26.60 222  17.5
2 3 10.85 014   7
; etc
*end somewhere</programlisting>

<Para>The default values for the standard deviations are those for
BCRA grade 5. Note that it is good practice to keep the *include
Grade3 within *Begin and *End commands otherwise it will apply
to following survey data, which may not be what you intended.
</Para>

</Sect2>

<Sect2><Title>Specify different accuracy for a leg</Title>

<Para>For example, suppose the tape on the plumbed leg in this survey
is suspected of being less accurate than the rest of the survey because
the length was obtained by measuring the length of the rope used to rig
the pitch.  We can set a higher sd for this one measurement and use a
*begin/*end block to make sure this setting only applies to the one
leg:
</Para>

<programlisting>
2 1 26.60 222  17.5
2 3 10.85 014   7
2 4  7.89 254 -11
*begin
; tape measurement was taken from the rope length
*sd tape 0.5 metres
4 5  34.50 - DOWN
*end
5 6  9.29 271 -28.5</programlisting>

<!-- FIXME also *calibrate and *instrument? Except rope is measure with the
tape... -->
</Sect2>

<Sect2><Title>Enter Repeated Readings</Title>

<Para>If your survey data contains multiple versions of each leg (for example,
pockettopo produces such data), then provided these are adjacent to one another
Survex 1.2.17 and later will automatically average these and treat them as a
single leg.
</Para>

</Sect2>

<Sect2><Title>Enter Radiolocation Data</Title>

<!-- FIXME comments from David Gibson here -->
<Para>This is done by using the *SD command to specify the appropriate
errors for the radiolocation `survey leg' so that the loop closure
algorithm knows how to distribute errors if it forms part of a loop.
</Para>

<Para>The best approach for a radiolocation where the underground station
is vertically below the surface station is to represent it as a
plumbed leg, giving suitable SDs for the length and plumb angle. The
horizontal positioning of this is generally quite accurate, but the
vertical positioning may be much less well known. E.g: we have a
radiolocation of about 50m depth +/- 20m and horizontal accuracy of
+/- 8m. Over 50m the +/-8m is equivalent to an angle of 9 degrees, so
that is the expected plumb error. 20m is the expected error in the
length. To get the equivalent SD we assume that 99.74% of readings will
be within 3 standard deviations of the error value. Thus we divide the
expected errors by 3 to get the SD we should specify:
</Para> <!-- 3 SD? or same as BCRA3.SVX, etc -->

<programlisting>
*begin
*sd length 6.67 metres
*sd plumb 3 degrees
surface underground 50 - down
*end</programlisting>

<Para>
We wrap the radiolocation leg in a *begin/*end block to make
sure that the special *sd settings only apply to this one leg.
</Para>

<Para>For more information on the expected errors from radiolocations
see Compass Points Issue 10, available online at
<ulink url="http://www.chaos.org.uk/survex/cp/CP10/CPoint10.htm">http://www.chaos.org.uk/survex/cp/CP10/CPoint10.htm</ulink>
</Para>

</Sect2>

<Sect2><Title>Enter Diving Data</Title>

<Para>Surveys made underwater using a diver's depth gauge can be
processed - use the *Data command to specify that the following data
is of this type.
</Para>

</Sect2>

<Sect2><Title>Enter Theodolite data</Title>

<Para>
Theodolite data with turned angles is not yet explicitly catered
for, so for now you will need to convert it into equivalent legs in
another style - normal or cylpolar are likely to be the best choices.
</Para>

<Para>
If there is no vertical info in your theodolite data then you should
use the cylpolar style and use *sd command to specify very low
accuracy (high SD) in the depth so that the points will move in the
vertical plane as required if the end points are fixed or the survey
is part of a loop.
</Para>

</Sect2>

</Sect1>

<Sect1><Title>General: How do I?</Title>
<?dbhtml filename="genhowto.htm">

<Sect2><Title>Create a new survey</Title>

<Para>You simply create a text file containing the relevant survey data,
using a text editor, and save it with a suitable name with a <filename>.svx</filename>
extension. The
easiest way is to look at some of the example data and use that
as a template. Nearly all surveys will need a bit of basic info
as well as the survey data itself: e.g. the date (*date), comments
about where, what cave, a name for the survey (using *begin and *end),
instrument error corrections etc. Here is a typical survey file:
</Para>

<Para>All the lines starting with ';' are comments, which are ignored
by <Application>Survex</Application>. You can also see the use of 'DOWN' for plumbs, and
*calibrate tape for dealing with a tape length error (in this case
the end of the tape had fallen off so measurements were made from the
20cm point).</Para>

<programlisting>
*equate chaos.1 triassic.pt3.8
*equate chaos.2 triassic.pt3.9

*begin chaos
*title "Bottomless Pit of Eternal Chaos to Redemption pitch"
*date 1996.07.11
*team "Nick Proctor" compass clino tape
*team "Anthony Day" notes pictures tape
*instrument compass "CUCC 2"
*instrument clino "CUCC 2"
;Calibration: Cairn-Rock 071 072 071,  -22 -22 -22
;       Rock-Cairn 252 251 252,  +21 +21 +21
;Calibration at 161d entrance from cairn nr entrance to
;prominent rock edge lower down. This is different from
;calibration used for thighs survey of 5 July 1996

*export 1 2

;Tape is 20cm too short
*calibrate tape +0.2

1 2 9.48 208 +08
2 3 9.30 179 -23
3 4 2.17 057 +09
5 4 10.13 263 +78
5 6 2.10 171 -73
7 6 7.93 291 +75
*begin
*calibrate tape 0
8 7 35.64 262 +86 ;true length measured for this leg
*end
8 9 24.90 - DOWN
10 9 8.61 031 -43
10 11 2.53 008 -34
11 12 2.70 286 -20
13 12 5.36 135 +23
14 13 1.52 119 -12
15 14 2.00 036 +13
16 15 2.10 103 +12
17 16 1.40 068 -07
17 18 1.53 285 -42
19 18 5.20 057 -36
19 20 2.41 161 -67
20 21 27.47 - DOWN
21 22 9.30 192 -29
*end chaos</programlisting>

</Sect2>

<Sect2><Title>Join surveys together</Title>

<Para>Once you have more than one survey you need to specify how they
link together. To do this use *export to make the stations to be
joined accessible in the enclosing survey, then *equate in the
enclosing survey to join them together.
<!-- FIXME example -->
</Para>

</Sect2>

<Sect2><Title>Organise my surveys</Title>

<Para>This is actually a large subject. There are many ways you can
organise your data using <Application>Survex</Application>. Take a look at the example dataset
for some ideas of ways to go about it.
</Para>

<Sect3><Title>Fixed Points (Control Points)</Title>

<Para>The *fix command is used to specify fixed points (also know as control
points).  See the description of this command in the "Cavern Commands"
section of this manual.
</Para>

</Sect3>

<Sect3><Title>More than one survey per trip</Title>

<Para>Suppose you have two separate bits of surveying which were done on the
same trip.  So the calibration details, etc. are the same for both.  But you
want to give a different survey name to the two sections.  This is easily
achieved like so:
</Para>

<programlisting>
*begin
*calibrate compass 1.0
*calibrate clino 0.5
*begin altroute
; first survey
*end altroute
*begin faraway
; second survey
*end faraway
*end</programlisting>

</Sect3>

</Sect2>

<Sect2><Title>Add surface topography</Title>

<Para>Survex 1.2.18 added support for loading terrain data and rendering it as
a transparent surface.  Currently the main documentation for this is maintained
as a <ulink url="https://trac.survex.com/wiki/TerrainData">wiki page</ulink>
as this allows us to update it between releases.
</Para>

<Para>
We recommend using this new code in preference, but previously the simplest
approach was to generate a <filename>.svx</filename> file with the surface mesh
in and display it with the survey data.
</Para>

<Para>
It is possible to generate
a mesh or contours overlaying your area by various means.  NASA have made
1 arc-second (approximately 30m) terrain data available for the USA for
some years, with only 3 arc-second data available for other countries.
However, starting in 2014 they're gradually making 1 arc-second data
available for more countries.
</Para>

<Para>
If you want a better resolution that this, reading heights from the
contours on a map is one approach.  It's laborious, but feasible for
a small area.
</Para>

<Para>
Details of several methods are given in the BCRA Cave Surveying
Group magazine Compass Points issue 11, available online at
<ulink url="http://www.chaos.org.uk/survex/cp/CP11/CPoint11.htm#Art_5">http://www.chaos.org.uk/survex/cp/CP11/CPoint11.htm#Art_5</ulink>
</Para>

<Para>If you're using another program to generate a <filename>.svx</filename> file for the surface
mesh, it's best to use the NOSURVEY data style.
Simply fix all the grid intersections at the correct
coordinates and height, and put legs between them using the NOSURVEY style.
Here's a grid of 4 squares and 9 intersections:
</Para>

<programlisting>
*fix 00 000 000 1070
*fix 01 000 100 1089
*fix 02 000 200 1093

*fix 10 100 000 1062
*fix 11 100 100 1080
*fix 12 100 200 1089

*fix 20 200 000 1050
*fix 21 200 100 1065
*fix 22 200 200 1077

*data nosurvey station

00
01
02

10
11
12

20
21
22

00
10
20

01
11
21

02
12
22</programlisting>

<Para>
This is far simpler than trying to create fake tape/compass/clino legs of
the right length for each line in the mesh.  It's also very fast to process
with cavern.
</Para>

</Sect2>

<Sect2><Title>Overlay a grid</Title>

<Para>Aven is able to display a grid, but this functionality isn't currently
available in printouts.
You can achieve a similar effect for now by creating a <filename>.svx</filename> file
where the survey legs form a grid.
</Para>

</Sect2>

<Sect2><Title>Import data from other programs</Title>

<Para><Application>Survex</Application> supports a number of features to help with importing
existing data. You can specify the ordering of items on a line using *Data
(see <Application>Survex</Application> Keywords above), and you can specify the characters used
to mean different things using *Set (see <Application>Survex</Application> Keywords above).
</Para>

<Para>The Ignore and Ignoreall options to the *Data command are often
particularly useful, e.g. if you have a dataset with LRUD info or comments
on the ends of lines.
</Para>

<Sect3><Title>Changing Meanings of Characters</Title>

<Para>e.g. if you have some data with station names containing the 
characters '?' and '+' (which are not permitted in a name by default)
then the command:
</Para>

<programlisting>
*SET NAMES ?+</programlisting>

<Para>
specifies that question marks and plus signs are permitted in station names.
A-Z, a-z, and 0-9 are always permitted. '_' and '-' are also permitted by
default, but aren't in this example.
</Para>

<Para>If your data uses a comma ',' instead of a decimal point, then
you use
</Para>

<programlisting>
*SET DECIMAL ,</programlisting>

<Para>to specify that ',' is now the decimal separator instead of '.'.
</Para>

<!-- FIXME
<Para>Note that there are plenty of ways you can use this facility to
completely confuse the software, as it may not be able to work out what is
going on, or it may simply be ambiguous. It can cope with some ambiguity (e.g.
the '-' character is used both for 'MINUS' and for 'OMIT'), but there are
limits. If you have a dataset that you can not make <Application>Survex</Application>
understand, then send it to us, and we will see what can be done.
</Para>
-->

</Sect3>

<!--
 Nobody seems to have the CfH convertor...
 but it's probably no longer useful anyway

<Sect3><Title>Other Converters</Title>

<Para>We have an Excel 5 macro for converting The Lotus 123 spreadsheets
used by the German survey software Cad F&uuml;r H&ouml;hlen into
<Application>Survex</Application> data files. Other converters may also come to be available.
These will normally be available via the
<ulink url="https://survex.com/"><Application>Survex</Application> Web pages</ulink>.
</Para>

</Sect3>
-->

</Sect2>

<Sect2><Title>Export data from <Application>Survex</Application></Title>

<Para>See Rosetta Stal in the Related Tools section of the Survex web
site.  This is a utility written by Taco van Ieperen and Gary Petrie.
Note though that this only supports a subset of the svx format,
and only work on Microsoft Windows.  The Survex support is limited
and doesn't understand the more recently added commands.</Para>

</Sect2>

<Sect2><Title>See errors and warnings that have gone off the screen</Title>

<Para>When you run <Application>Survex</Application> it will process the specified survey data
files in order, reporting any warnings and errors.  If there are no
errors, the output files are written and various statistics about the
survey are displayed. If there are a lot of warnings or errors, they can
scroll off the screen and it's not always possible to scroll back to
read them.
</Para>

<Para>The easiest way to see all the text is to use <command>cavern
--log</command> to redirect output to a <filename>.log</filename> file,
which you can then inspect with a text editor.
</Para>

<!-- <command>cavern cavename &gt; tmpfile</command> -->

</Sect2>

<Sect2><Title>Create an Extended Elevation</Title>

<Para>Use the Extend program. This takes <filename>.3d</filename> files and
'flattens' them.  See 'Extend' for details.
</Para>

</Sect2>

</Sect1>

<!--
<Sect1><Title>Appendices</Title>
<?dbhtml filename="appendix.htm">

<Para>Files provided
</Para>

<Para>Command specification
</Para>

</Sect1>
-->
<Sect1><Title>Working with Larry Fish's Compass</Title>
<?dbhtml filename="compass.htm">

<Para>
Survex can read Compass survey data - both raw data (.DAT and .MAK
files) and processed survey data (.PLT and .PLF files).  You can even
use <command>*include compassfile.dat</command> in a <filename>.svx</filename> file and
it'll work!
</Para>

<Para>
One point to note (this tripped us up!): station names in DAT files are
case sensitive and so Survex reads DAT files with the equivalent of
<command>*case preserve</command>.  The default in SVX files is
<command>*case lower</command>.  So this won't work:

<programlisting>
*fix CE1 0 0 0
*include datfilewhichusesCE1.dat</programlisting>

Because the CE1 in the *fix is actually interpreted as ce1.  This is
what you have to do:

<programlisting>
*begin
*case preserve
*fix CE1 0 0 0
*include datfilewhichusesCE1.dat
*end</programlisting>
</Para>

</Sect1>

<Sect1><Title>Mailing List</Title>
<?dbhtml filename="maillist.htm">

<Para>The best way to contact the authors and other Survex users is the
Survex mailing list - for details visit:
<ulink url="https://survex.com/maillist.html">https://survex.com/maillist.html</ulink>
</Para>

<Para>We'd be delighted to hear how you get on with <Application>Survex</Application> and
welcome comments and suggestions for improvements.</Para>

<Para>
And we'd love you to contribute your skills to help make <Application>Survex</Application> even
better.  Point out areas of the documentation which could be made clearer, or
sections which are missing entirely.  Download test releases, try them out, and
let us know if you find problems or have suggestions for improvements.
If there's no translation to your language, you could provide one.
Or if you're a developer, <emphasis>"Say it with code"</emphasis>.  There's
plenty to do, so feel free to join in.
</Para>

</Sect1>

<Sect1><Title>Future Developments</Title>
<?dbhtml filename="future.htm">

<Para>
Now that <Application>Survex</Application> has reached version 1.0, we are continuing progress
towards version 2, in a series of steps, evolving out of 
Survex 1.0.  The GUI framework is being based on aven, with
the printer drivers and other utility programs being pulled in
and integrated into the menus.</Para>

<Para>Aven is built on <Application>wxWidgets</Application>, which means that it can easily support
Unix, Microsoft Windows, and Mac OS X.</Para>

<Para>More information on our plans is on the <ulink
url="https://survex.com/">web site</ulink>.
</Para>

</Sect1>

</article>