An RSE can be simply:

       o  A record source:

           YACHTS
           CURRENT
           A

       o  A record source with a Boolean expression and a SORTED BY
          clause:

          YACHTS  WITH PRICE GT 0  SORTED BY LOA

       o  A record source with a Boolean expression, REDUCED TO clause,
          and a SORTED BY clause:

          YACHTS  WITH PRICE GT 0  REDUCED TO TYPE, LOA SORTED BY LOA

       o  Multiple record sources with a common field:

          YACHTS CROSS OWNERS OVER TYPE

       o  Multiple record sources with context variables:

          A IN YACHTS CROSS B IN OWNERS OVER BUILDER WITH A.MODEL NE B.MODEL