Format of XMS handle info record:
Offset	Size	Description	)
 00h	WORD	handle
 02h	WORD	flags
		bit 0: handle usable by Windows
			(already in use when Windows started if clear)
		bit 1: reserved (0)
 04h	DWORD	size in KB (may be zero, used only if flags bit 0 set)
 08h	DWORD	physical address (only if flags bit 0 set)