              3

      If data for all of the above surfaces are loaded, then
      data for surface 1 can be specified by either

         'SURFACES = 1'

      or

         'SURFACES = &quot;Mars MEGDR 128 PIXEL/DEG&quot;'

      Double quotes are used to delimit the surface name because
      it contains blank characters.

      To use data for surfaces 2 and 3 together, any
      of the following surface lists could be used:

         'SURFACES = 2, 3'

         'SURFACES = &quot;Mars MEGDR  64 PIXEL/DE