<para>
  This is the format used by the software that comes with the <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.semsons.com/i747bldalogp.html">Transystem i-Blue747 GPS</link>.
</para>

<para>
  Notice that the iBlue 747 logs the sum of "height above sealevel" and "height of geoid above WGS84".   If precise altitude matters to you, check out the <link linkend="filter_height">height filter</link> which allows you to compensate for this.
</para>
