W may be found in a SPICE PCK kernel. 
 
   The earth, moon, and sun are exceptions: planetographic longitude 
   is measured positive east for these bodies. 
 
   If you wish to override the default sense of positive longitude 
   for a particular body, you can do so by defining the kernel 
   variable 
 
      BODY&lt;body ID&gt;_PGR_POSITIVE_LON 
 
   where &lt;body ID&gt; represents the NAIF ID code of the body. This 
   variable may be assigned either of the values 
 
      'WEST' 
      'EAST' 
 
   F