Bitfields for SK-UPPS receive status:
Bit(s)	Description	)
 0-2	reserved (0), currently unused
 3	frame check sequence (FCS) error
 4	overflow (frame too long)
 5	framing error
 6	reserved (0), currently unused
 7	non-LLC frame (see #03850 [bit 8])
 8-15	reserved (0), currently unused
Notes:	The protocol's Receive Upcall routine will be called whenever a frame
	  matching the specified frame type is received. A received frame is
	  passed to the protocol in the Mbuf's DATA area at OFFSET and its size
	  is LENGTH bytes.
	The receive status passed to the Receive Upcall in register AL is
	  always zero, except for protocols using "non-LLC" mode (8 of PCB's
	  protocol mode field) or "promiscuous" mode together with "receive
	  error frames" (0 & 3).
	Upcalls are FAR routines and must return with a RET FAR. If the Carry
	  Flag is set on return from a Receive or Transmit Upcall, then ES:BX
	  must point to an Mbuf, which the DLI will then pass to the RELEASE
	  BUFFER function (see AX=0005h). See also notes for PROTOCOL MODE.