Subject: APPC protocols clarification

From: [email-masked] (Dave Finnie)
Date: Wed, 7 Sep 94 14:32:25 EST

In the APPC Peer Protocols reference, on Page 10-6, is the
main working procedure for HS (PROCESS_LU_LU_SESSION).

After determining that a record for PS exists, the 
pseudo-code contains the following test:

"if the session is not between brackets (FSM_BSM_FMP19 != BETB) or
    half-session is not expecting a response (FSM_CHAIN_SEND_FMP19 != PEND_RSP) or
    half-session is not expecting a reply (FSM_CHAIN_SEND_FMP19 != PEND_RCV_REPLY) then
   ..."

How should one interpret this test ? With no bracketing, this
condition will always be true, since regardless of the value
of FSM_CHAIN_SEND_FMP19, it will either be not PEND_RSP or not
PEND_RCV_REPLY (even if it is one of these values).

After reading the non-formal description of HS, my
version of the test would have replaced the "or"s with
"and"s . This is because we should process the PS
request so long as the session is in bracket _and_
not (expecting a response or expecting a reply). By
boolean logic, this turns into:

  "not between brackets _and_
   not expecting a response _and_
   not expecting a reply"

Could you please clarify ?

Dave