NAME
        MissingDataMask

   DESCRIPTION
        Creates a simple binary lattice with 0's at the nodes where the data
          equals the specified "missing value", 1's otherwise..

   INPUTS

      Data Array -- Lattice
         (3-D, float).
         Data containing (possible) "missing values"; ie, nodes with a 
           special value indicating that no valid data exists at that point.

   WIDGETS

      Missing Data Indicator -- Dial
         Special value indicating no valid data at that point.

   OUTPUTS

      Mask Array (0/1) -- Lattice
         (3-D, float).
         Output binary lattice containing 1's where valid data exists,
           0's otherwise.

   KNOWN PROBLEMS
      Awfully simple; duplicates some functionality in ScaleLatNode.

   SEE ALSO
      ScaleLatNode, ScaleLat, ScaleLatPerim, ScaleLatCurv, LatMod