struc IOCTLRequest              ; Device-Driver functions 13h, 19h
 giLength       db ?            ; Length of structure, in bytes
 giUnit         db ?            ; Unit number (block device only)
 giFunction     db ?            ; Function number (13h or 19h)
 giStatus       dw ?            ; Status
 giReserved1    db 8 dup (?)    ; Reserved
 giCategory     db ?            ; INPUT: device category
 giMinorCode    db ?            ; INPUT: minor code
 giReserved2    dd ?            ; Reserved
 giIOCTLData    dd ?            ; INPUT: IOCTL data address
ends                            ; = 23d bytes