The following example defines a record that contains MISSING
       VALUE clauses:

       DTR> DEFINE DOMAIN THINGS USING THINGREC ON THINGS;
       DTR> DEFINE RECORD THINGREC USING
       DFN> 01 THINGS.
       DFN>    03 NUM PIC 9(5)
       DFN>       MISSING VALUE IS 11111
       DFN>       EDIT_STRING IS ZZ,Z99?"***MISSING***".
       DFN>    03 STR PIC X(10) MISSING VALUE IS "EMPTY"
       DFN>       EDIT_STRING IS X(10)?"***MISSING***".
       DFN> ;

       DTR>

       The following example defines a new domain based on YACHTS that
       uses a new missing value and a MISSING VALUE edit string:

       DTR> DEFINE DOMAIN YACHTS_PRICE_LIST USING YPL_REC ON YPL.DAT;
       DTR> DEFINE RECORD YPL_REC USING
       DFN> 01 BOAT.
       DFN>    03 TYPE.
       DFN>       05 BUILDER PIC X(10).
       DFN>       05 MODEL PIC X(8).
       DFN>    03 PRICE PIC 9(5) MISSING VALUE IS 0
       DFN>       EDIT_STRING $$$,$$$?"NOT LISTED".
       DFN> ;
       [Record is 23 bytes long.]
       DTR> DEFINE FILE FOR YACHTS_PRICE_LIST KEY = TYPE
       DTR> READY YACHTS_PRICE_LIST AS YPL WRITE
       DTR> READY YACHTS
       DTR> YPL = YACHTS WITH LOA GT 35
       DTR> FIND YPL WITH PRICE MISSING
       [12 records found]
       DTR> PRINT FIRST 3 CURRENT

        BUILDER    MODEL     PRICE

       BLOCK I.   40       NOT LISTED
       CABOT      36       NOT LISTED
       DOWN EAST  38       NOT LISTED

       DTR>