A series of GT routines was created so that a single piece of information
can be extracted from a structure, whether the structure was a `roadmap'
or an `index' (the data are saved in a different location). The routines
also allow for conversions to a string mnemonic or to physical units.
It is possible to get a list of what the different values are by typing a
command like:
IDL> print, gt_filta()
It is also possible to convert the output value to the string mnemonic by using the
/STRING switch. For example:
IDL> print, gt_filta(roadmap, /string)
This command only works for the routines which return a coded value.
A list of all of the GT routines currently available are:
