SGWH

     SGWH is the ending valid time for the significant wave height data, 
     the height intervals and colors.  Skip is a value that indicates how 
     many data points to skip when plotting.

       Data type | End time | Height intervals | colors | Skip |
       Time stamp interval | Time stamp color 

     The data type is a selection to plot SGWH (Jason-1), SGWHA (Altika), 
     SGWHC (CryoSat), SGWHE (Envisat), SGWHG (GFO), or SGWH2 (Jason-2). 

     The ending time is the latest time for which SGWH 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 SGWH data
     for the preceding 4 hours. ALL is not accepted as an ending time for 
     SGWH data.

     The height intervals and colors may each be specified using either a list
     separated by semicolons or a range in the form first-last-increment.
     Height intervals are given in feet.  If any color is missing, a default 
     will be used.  If no interval and color are given, a single height 
     interval of 200 feet will be used.  This means that any significant wave 
     height less than 200 feet will be plotted.  The default color for the 
     single height is green.  

     The Skip value is an integer used for skipping of data when plotting 
     the heights.

     The time stamp interval is the time interval in minutes. Time stamp 
     color is the color of the time stamps. The default value is 30 for the
     time stamp interval and 5 for the time stamp color.