TRAKE

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

       End time | Color | Skip

     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
     TRAKE data for the preceding 6 hours. ALL is not accepted as an ending 
     time for TRAKE 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.