Int 21 Fn 2B  - Elres V1.1 - Installation Check                            [U]

   AH = 2Bh
   CX = 454Ch ('EL')
   DX = 5253h ('RS')

Return: ES:BX -> ELRES history structure (see below)
   DX = DABEh (signature, DAve BEnnett)
Program: ELRES is an MS-DOS return code (errorlevel) recorder by David H.
     Bennett which stores recent errorlevel values, allows them to be
     retrieved for use in batch files, and can place them in an
     environment variable

See Also: AH=4Bh"ELRES",AH=4Dh

Format of ELRES history structure:
Offset Size    Description
 00h   WORD    number of return codes which can be stored by following buffer
 02h   WORD    current position in buffer (treated as a ring)
 04h  N BYTEs  ELRES buffer