AGTEK is using GPX files to record tracks and simulations on the Android platform. The use of GPX may also be useful on other platforms, desktop computers, etc. The core portion of GPX is fine for most of our uses (currently - August 2012), but there are some additional bits of information we need. These extra pieces of information are coded into the GPX file using the extension mechanism. To be of maximum use, all AGTEK applications should use the same extensions. This document covers the format of the AGTEK GPX files so other applications can be as compatible as possible.

General comments about using GPX.

• All times are specified using the ISO 8601 standard. It is not correct to specify times in any other format.
• String data must be XML save, which generally means no “<” or “>” characters.
• GPX applications are free ignore extensions they do not understand
• The AGTEK extensions can not be required, but some parts of the application may not functional “normally”. The functions must not fail, however.
• Apropos of the GPX standard, coordinates must be LAT/LON/ELEV measured in decimal degrees, and meters of elevation.

See the GPX standard for the documentation on the standardized portions of the format.

An example GPX file looks like:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
 <gpx xmlns="http://www.topografix.com/GPX/1/1">
  <metadata>
    <link href="http://www.agtek.com">
      <text>AGTEK Earthworks</text>
    </link>
    <time>2012-05-21T14:29:24.360-0700</time>
  </metadata>
  <extensions>
     <agtek>
        <provider>Leica</provider>
     </agtek>
  </extensions>
  <trk>
    <name>5/21/12 2:29 PM</name>
    <trkseg>
      <trkpt lat="37.69882038778071" lon="-121.81280981721213">
        <ele>86.87749096378684</ele>
        <time>2012-05-21T14:29:25.171-0700</time>
        <extensions>
           <agtek>
              <status-fixtype>Fixed</status-fixtype>
              <status-satellite>8-0</status-satellite>
              <compass>64.245964</compass>
           </agtek>
        </extensions>
      </trkpt>
      <trkpt lat="37.69882042900191" lon="-121.81280982182977">
        <ele>86.87943022698164</ele>
        <time>2012-05-21T14:29:25.192-0700</time>
        <extensions>
           <agtek>
              <status-fixtype>Fixed</status-fixtype>
              <status-satellite>8-0</status-satellite>
              <compass>64.245964</compass>
           </agtek>
        </extensions>
      </trkpt>
      <trkpt lat="37.69882044902325" lon="-121.812809827169">
        <ele>86.88186285737902</ele>
        <time>2012-05-21T14:29:25.200-0700</time>
        <extensions>
           <agtek>
              <status-fixtype>Fixed</status-fixtype>
              <status-satellite>8-0</status-satellite>
              <compass>64.245964</compass>
           </agtek>
        </extensions>
      </trkpt>

      ...snip...

      <trkpt lat="37.69885776454766" lon="-121.81314775154998">
        <ele>86.83196703717113</ele>
        <time>2012-05-21T14:46:29.989-0700</time>
        <extensions>
           <agtek>
              <status-fixtype>Fixed</status-fixtype>
              <status-satellite>8-0</status-satellite>
              <compass>48.64595</compass>
           </agtek>
        </extensions>
      </trkpt>
    </trkseg>
  </trk>
</gpx>