TRAK

     TRAK is the ending time for the Altimetric Satellite Ground 
     Track Prediction data, and the color of the prediction.  Skip 
     is a value that indicates how many data points to skip when plotting.

       Data type | End time | Color | Skip

     The data type is a selection to plot. Currently there are five data
     types, TRAK1 (Jason-1), TRAK2 (Jason-2), TRAKE (Envisat), TRAKS 
     (Saral/Altika), and TRAKC (Cryosat).

     The ending time is the latest time for which prediction data will be 
     plotted.  The ending time is given as a GEMPAK date/time string.  Any
     missing items from the string will be filled in by the system time.  The 
     ending time may also be LAST.  LAST will use the system time and plot all
     TRAK data for the preceding 6 hours. ALL is not accepted as an ending 
     time for TRAK data.

     The Color may each be specified using a GEMPAK color in the range of
     1 - 32. If the color is missing, a defalut will be used.

     The Skip value is an integer used for skipping datapoints when plotting 
     the predictions. If the skip value is missing a default will be used.