GTrack subtype example. A) An ad hoc GTrack suptype specification based on the example GTrack file in Figure 4A, which is a conversion from the GFF file in Figure 3A. This and other GTrack subtypes are available from the GTrack website . B) A minimal GTrack header, parsable by fully compliant GTrack parsers. Note that the "Expand GTrack headers" tool, available from the GTrack website , can be used to expand headers of GTrack files using subtypes, in order for such files to be used in simpler parsers that do not support the subtype functionality.