Format of APPC/PC "Detach Physical Unit" control block:
Offset	Size	Description	)
 00h 12 BYTEs	reserved
 0Ch	WORD	2700h (verb "Detach Physical Unit")
 0Eh  6 BYTEs	00h
 14h	DWORD	(big-endian) return code (see #03668)
 18h	BYTE	00h  type: hard
		01h  type: soft