Int 15 Fn D602  - Later Ps/2s - Query Boot Reference Partition             [B]

   AX = D602h

Return: CF clear on success
       AH = 00h
       AL = status of reference-partition boot request
       00h boot not requested
       01h boot requested
   CF set on error
       AH = status (86h for function not supported)

See Also: AX=D601h/BL=00h