Bulletins from the Pacific Packet Radio Society - page 155
************************************************************************
* F_ * LDID * LSID * PNR * GSID * BC * NODE field * BCS *
************************************************************************
0 --- 2 ------ 5 ------ 8 ----- 9 ------15 -- 16 ------------16+n - 18+n*********************************
* A_ * LDID * LSID * PNR *
*********************************
0 --- 2 ------ 5 ----- 8 ----- 9Comments:
The 'A' packet uses reversed local IDs to simplify acknowledgement procedures; i.e., local source is the local destination of the 'A'-packet.
BC : Byte count of Node field (n) .
BCS : Block check sum, 2 bytes wide of total packet (18+n) bytes.
............ ____
............ {
BCS = ( / Wi ) mod 2~16 Wi = 2 byte word i
............ -------GSID: Global source (origin) of packet. Packet owner ID. 6 globally unique ASCII characters (for instance call sign).
LDID:Local destination of packet (=3 last bytes of global ID) The destination may contain one or more 'wildcard' characters (ASCII NULL = 00 hex) which matches any character in that position at the receiving node.
LSID:Local source (origin) of packet (=3 last bytes of global ID) No wildcards are allowed.
NODE:AN even number of bytes. This field is interpreted by the 'F' word after selection of the proper NODE environment.
PNR : Packet number, 1 byte. Two consecutive packets transmitted from some node to the same destination have to use distinct packet number.
73, Paul, W4RI
FILE QST.83.01.29.0.N6ECT
Date: January 29, 1983
From: Curtis, N6ECT
To: All Interested PacketeersSubject: Software Replacement for the SDLC 8273
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