<para>
   Convert track number 'index' from source into dmtlog format.
</para>
<para>
   The known variants of Tracklog 'digital mapping' files supports only
   one track per file. If you have more than one track in source
   (f.e MapSource and many others can do such heavy things), you
   can specify which track should by used for the conversion.
</para>
<para>
   The default index is 1 (the first track of a possible list of tracks).
</para>
<para>
   An example usage you can find at the <link linkend="fmt_ignrando">ignrando</link> format,
   which uses option <link linkend="fmt_ignrando_o_index">index</link> in same manner.
</para>
