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Subject:Re: SGML/FOSI/DSSL help needed. From:Chet Ensign <Chet_Ensign%LDS -at- NOTES -dot- WORLDCOM -dot- COM> Date:Mon, 19 Dec 1994 17:17:21 EDT
I can offer a little help.
<--differences between FOSI and DSSSL. I started off thinking both
were just formal methods for defining the format rules of a class
of document and that it is the job of various formatting
applications (e.g., Interleaf, WORD, FrameBuilder/Maker) to
interpret those rules so that the document can be reconstructed in
the application in all its formatted glory from its SGML-tagged instance.
Well, yes, pretty much. Dr. Charles Goldfarb's book "The SGML Handbook" talks
about the notion of SGML "semantics." The DTD itself was only envisioned as
part of the total "semantics" of a document, namely, its structure. Other
semantics -- such as format or behavior -- were to be the domain of other
standards or supplied by products.
Your description of FOSI and DSSSL strikes me as pretty close to the mark.
Basically, FOSI was invented because DSSSL wasn't around yet and people needed
a way to specify format semantics for CALS documents. FOSIs are DTDs that
contain detailed formatting instructions for the structure outlined in the
document DTD. FOSIs are pretty basic in what they can handle (because they were
originally designed to handle military technical documents) and the only
products that I know of that actively take advantage of them are ADEPT from
ArborText and WriterStation from Datalogics. Interleaf 5 <SGML> may also
exploit them, but I'm not sure. Word, Frame et al don't.
<-- For all other systems, special interpreters must be built, e.g.,
Interleaf's Instance Processor, to convert the SGML instance
to the proprietary formatting scheme. I am also under the impression that
as soon as the DTD or FOSI changes, the interpreter must be reprogrammed
because it cannot "learn" the new structure or format rules by itself.
Is this true? -->
Correct. Take, for example, MS's new SGML Author for Word. You need to set up a
template that will map SGML markup to Word styles so that when you import an
instance, you get a styled Word document. Obviously, if you change the DTD --
meaning you are changing the basic structure of the data!!! -- you *may* have
to change the conversion template. I say *may* because there are some
techniques people have worked on to associate processing with *classes* of
elements. Thus, even though you might add a new element to the DTD, by making
that element an instance of an element class, you can automatically associate
formatting instructions with it.
You are hitting one area of SGML where I think the tools are really weak right
now, and where I expect to see a lot of development occur in the next few
years. Especially as people like you and me define the problem and demand
<-- FOSI vs DSSSL. What is the difference? I've heard that the two are
incompatible with each other to the extent that a FOSI cannot even be
"filtered" into an equivalent DSSSL spec. True?false?-->
Neither. The big difference between the two is that DSSSL is a standard that is
still in draft form. FOSIs exist and they are supported. I have not yet read
the standard for DSSSL, but from what I know of its design, I think it will eat
FOSIs for breakfast. Remember -- a FOSI is just another DTD. Transforms are
going to be possible, possibly trivial.
<-- Are there FAQ documents for DTD, FOSI, DSSSL, SGML, that I can peruse?-->
Are you aware of comp.text.sgml? There's an FTP archive at ifi.uio.no that
should contain info on all these topics, and it is also the home of
comp.text.sgml, the SGML newsgroup. For what you are doing, you owe it to
yourself to subscribe.
<-- is anyone using SGML in an Interleaf environment? I'd very much like
to be put in contact with such individuals. Is there a SIG for that
I don't know any personally, and I've heard much grumbling about Interleaf's
support for SGML. However, I know someone at Interleaf who could probably
direct you to the right source of information. He is a gentleman named Harvey
Bingham and his email address is bingham -at- ileaf -dot- com -dot- He is a terrific guy and
very knowledgeable. He has been in on SGML from the start.
So just out of curiousity, why are you going after SGML in the first place? I
am writing a book on the subject and I'm interested in talking to people whose
organizations are adopting SGML. I'd like to talk more about what you are
Hope this helped.
Director, Electronic Publishing
Logical Design Solutions, Inc.
Email: chet -at- lds -dot- com
Email (home): censign -at- interserv -dot- com