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From: jwf@hpctdia.HP.COM (John Freeborg)
Newsgroups: comp.protocols.iso
Subject: Re: question about SPDU
Message-ID: <5910005@hpctdia.HP.COM>
Date: 7 Jun 90 19:52:31 GMT
References: <9006051437.AA12834@ucbvax.Berkeley.EDU>
Organization: Hewlett-Packard CTD, Colo. Spgs.
Lines: 21


   The concatenation rules specify that a GT SPDU (category 0) must ALWAYS
be prepended to a DT SPDU (category 2).  So often times you will see a
session PDU such as:

	01-00-01-00   followed by a bunch of data.  This is an "empty" 
GT SPDU concatenated with a DT SPDU (both LIs are 0).

You should never see a DT SPDU by itself since category 2 SPDUs must be 
concatenated with another SPDU.

Hope this helps,
   John


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John W. Freeborg			Hewlett-Packard Company
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