C*
     C* Parameters:
     C* ----------
     C* Field  Lng Description                         Value
     C* -----  --- ----------------------------------- ------
     C* @@@RTN 1A  Control Code                        note 1
     C* @@@MSI 7A  Message Id.  (Normal IBM format)
     C* @@@MSF 10A Message file
     C* @@@RRQ  1A Reply Box Required in the Window    note 2   Optional
     C* @@@RPY  V  Reply - 1 -> 10 Alpha               note 3     "  "
     C* @@MDTA     Up to 120 character for messages               "  "
     C*            containing message data (&1 , &2 etc)
     C*            Prime using *MSDTA,n In 4GL
     C* @@@STL 2,0 Variable Start Line                 note 4     "  "
     C* @@@VPG 10A Validation Program Name             note 5     "  "
     C* @@@TNM  6A Validman Table Name if pgm is VALIDMAN         "  "
     C*
     C* Notes:
     C* ------
     C* 1. Control code values on entry to the macro are:
     C*    ' ' = Normal Size window (F1 from here to show large window)
     C*    'L' = Normal Size window positioned to the left of the display
     C*    'C' = Normal Size window positioned in the centre of the display
     C*    'R' = Normal Size window positioned to the right of the display
     C*    'B' = Direct to Big (F1) window (Second level msg text displayed)
     C*    'I' = I.B.M. Window (OS/400 release 2.3 and above only)
     C*    Return code on exit is 'X' if F3 selected
     C*    Return code on exit is 'P' if F12 selected
     C*
     C* 2. Optional parameter Reply Box Required
     C*    If not passed then only the message is displayed. User presses
     C*    Enter or F3 or F12.
     C*    Values are:
     C*    ' ' - Same as not passed
     C*    'S' - Short 'Y' / 'N' reply (validated). Box size = 1
     C*    'Y' - 'YES' / 'NO ' reply (validated). Box size = 3
     C*    '*' - '*YES' / '*NO ' reply (validated). Box size = 4
     C*    '1' -> '9' or '0' - Reply box size from 1 -> 9 or 10.
     C*
     C* 3. A default reply can be forced into this box on entry into
     C*    the macro, otherwise prime with Blanks.
     C*    Field size accepting reply should correspond to box size
     C*    indicated by @@@RRQ.
     C*
     C* 4. For standard size (non IBM) window the start line can be
     C*    controlled by this 2 digit field.
     C*    Column / line position is automatic for IBM windows.
     C*
     C* 5. The entered reply can be validated by VALIDMAN or a
     C*    Validman style finder program. Enter the name of your
     C*    own Validman style finder to validate the entered reply
     C*    or "VALIDMAN"
     C*    If you use VALIDMAN then you must enter the VM table name
     C*    that Validman must check against. (Parm @@@TNM)
     C*