/* $DOC$
   $NAME$
      ft_Descend()
   $CATEGORY$
      Conversion
   $ONELINER$
      Create a descending index key value
   $SYNTAX$
      ft_Descend( <exp> ) -> <value>
   $ARGUMENTS$
      <exp> is any expression of character, numeric, date, or logical type.
   $RETURNS$
      The inverse of <exp>
   $DESCRIPTION$
      This function is a replacement for CA-Cl*pper's Descend() function,
      which is known to produce memory corruption occassionally.
   $EXAMPLES$
      ? ft_Descend( 1 )      // Returns -1
   $SEEALSO$
      ft_XToY()
   $END$
 */