##  Examples of procedure overlaying.


    PROCEDURE Chk_Value (Fld  IN date) IS
    BEGIN
       if Fld not between to_date(‘01-JAN-80’)
                      and to_date(‘31-DEC-99’) then
          raise form_application_error ( -20001,
               ‘Invalid Date Value Entered’);
       end if;
    END;


    PROCEDURE Chk_Value (Fld  IN char) IS
    BEGIN
       if Fld not between ‘A’ and ‘ZZZZZZZZZ’ then
          raise form_application_error ( -20001,
               ‘Invalid Alpha Value Entered’);
       end if;
    END;


    PROCEDURE Chk_Value (Fld  IN number) IS
    BEGIN
       if Fld not between 0 and 99999999 then
          raise form_application_error ( -20001,
               ‘Invalid Numeric Value Entered’);
       end if;
    END;



##  These procedures can be called (overlayed) by :

    BEGIN
       Chk_Value ( sysdate );
       Chk_Value ( ‘PETER’ );
       Chk_Value ( 4723764 );
    END;