Format of FaxBIOS PDIR_OPEN command buffer:
Offset	Size	Description	)
 00h 12 BYTEs	common data (see #02935)
 0Ch 80 BYTEs	Phone Directory token
 5Ch 80 BYTEs	sort order token
 ACh	WORD	open Mode (0 = read, 1 = write)
 AEh	WORD	Phone Directory handle
 B0h	WORD	number of people
 B2h	WORD	number of groups
 B4h	WORD	bitmap of fields supported by partial read
 B6h  6 BYTEs	future expansion
 BCh	WORD	structure size