.TP
IT(tracks)
Can be one or more ASCII, native binary, or COARDS netCDF 1-D data files.
To supply the data files via a text file with a list of tracks (one per record),
specify the name of the track list after a leading equal-sign
(e.g., =tracks.lis).  If the names are missing their file extension we will
append the suffix specified for this IT(TAG).  Track files will be searched
for first in the current directory and second in all directories listed in
BD($X2SYS_HOME)/IT(TAG)/IT(TAG)_paths.txt (if it exists). [If BD($X2SYS_HOME)
is not set it will default to BD($GMT_SHAREDIR)/x2sys]. (Note: MGD77 files will
also be looked for via BD(MGD77_HOME)/mgd77_paths.txt and *.gmt files will be
searched for via BD($GMT_SHAREDIR)/mgg/gmtfile_paths).