Format of ISOLAN Transfer Control Block:
Offset	Type	Description	)
 00h	BYTE	command code
		B3h Status
		F2h Activate
		F3h Deactivate
		F4h Send Data
 01h	BYTE	command identity
 02h	BYTE	virtual circuit ID
 03h	WORD	buffer length
 05h	DWORD	buffer pointer
 09h	BYTE	expedited data flag
 0Ah	BYTE	cancelable flag
 0Bh 16 BYTEs	local network address
 1Bh 16 BYTEs	remote network address
 2Bh	DWORD	asynchronous notification routine
 30h	DWORD	local network number
 34h	DWORD	remote network number
 38h	BYTE	call timeout
 39h	BYTE	not used
 3Ah  8 BYTEs	reserved
 42h	BYTE	command code extension
 43h	WORD	Blue Book MAC type