Path: utzoo!attcan!uunet!van-bc!ubc-cs!news-server.csri.toronto.edu!rutgers!att!cbnewsi!hrs1
From: hrs1@cbnewsi.att.com (herman.r.silbiger)
Newsgroups: comp.text.sgml
Subject: Re: What about the DTD
Summary: SGML interchange not Open
Message-ID: <1990Oct5.003326.4284@cbnewsi.att.com>
Date: 5 Oct 90 00:33:26 GMT
References: <8149@mcshh.hanse.de>
Organization: AT&T Bell Laboratories
Lines: 30

In article <8149@mcshh.hanse.de>, schiers@mcshh.hanse.de (Carsten Schiers) writes:
> Hello,
> 
> is the Document Type Definition (DTD) part of an SGML text interchange?
> To specify my question: does a software product, e.g. a publishing
> system, which tells to be able to use SGML format, have to be able to
> read an SGML document and *any* DTD? As I understand, then it has to 
> read the DTD, which is something like a grammmar for me, and then parse
> the text, using this DTD.
> 
> I ask this, because a software manufacturer tells me, I have to send the
> DTD for my special problem to him, and then he will return a special 
> filter for documents which behave like this DTD. So anytime I have a new
> type of document, I have to buy a new filter. 

SGML encoded documents cannot be used in an Open Interchange environment,
since, as you have found out, the document cannot be interpreted unless you
also have the DTD.  This is one of the reasons that ODA adopted a standardized
architecture.

While it is true that ODA applications also must conform to a Document 
Application Profile (DAP), these are hierarchical subsets of the complete
standard.  If you conform to the highest level, you can understand all the
lower levels.  In SGML, conforming to one DTD does not help you with the others.

In the future, the use of ODL may provide the advantages of a standardized
architecture to SGML applications.

Herman Silbiger
hsilbiger@attmail.com