MASK             Return a Bit Mask                                   Operator

   MASK recordFieldName
   MASK record

    Returns a bit pattern representing the bits used by a particular field
    of a record.  Bits used by the field will by 1, while those not used
    by the field will be 0.

       Notes:     The recordFieldName must be the name of a record field.
                  Record must be the name of a record.