<para>
This option tells GPSBabel whether to read (on input) or write (on output)
GPVTG sentences.  The default is to read or write GPVTG sentences.  To
disable GPVTG sentences, specify <option>gpvtg=0</option>.
</para>
<para>
GPVTG sentences contain information about the heading and the speed at the
time of the fix.  They do not contain any location information; for that
you will need either or both of GPGGA or GPRMC.
</para>
