Re: tlug: SGML

[Matt Gushee <matt@example.com>]

Thanks to Steve for helping to clarify yet another murky issue. I just 
want to quibble with a couple of minor points.

Stephen J. Turnbull writes:

 >     Matt> everything for them w/out much effort, but good free tools
 >     Matt> are not all that abundant, I think (though I'm still just a
 >     Matt> beginner).
 > 
 > sp and jade are excellent, and pretty much all that you need.

"All that you need"? That depends very much on what you want to
do. Jade is excellent inasmuch as it does what it does reliably and
with a minimum of fuss and bother. By the way, its author, James
Clark, is also the author of groff and nsgmls -- arguably one of the
great unsung heroes of the free software world.

Jade is probably the best available implementation of the DSSSL
standard, but it is rather limited (so far ... it's getting better all
the time). To be specific, it supports a subset of DSSSL called the
"DSSSL Online" spec, which has many useful features but leaves out
some important ones that people often want for print documents
... most notably, the DSSSL standard defines a 'page-sequence' object
and a 'simple-page-sequence' object. Jade implements only
'simple-page-sequence', which means you don't have columns, you don't
have (if I'm remembering correctly) much flexibility with page
numbering, headers and footers, you don't have a whole lot of things
that you might want in a formal, published document.

 >     ash> I was thinking it was more like TeX, in that it takes care of
 >     ash> formatting. Now I understand that this is not the case, that
 >     ash> the presentation ( formating, rendering ? ) of the SGML is
 >     ash> quite separate from it, which seems to be where DSSSL come
 >     ash> in.
 > 
 > No.  DSSSL is to SGML as objects are to methods.  That is, DSSSL
 > provides high level objects (like section headers), which can be
 > implemented in varying ways (bold vs. different font, numbered or
 > unnumbered) via methods.

Okay ... but I don't see what was wrong, in practical terms, with
Andy's understanding. And I don't see how an SGML element is a
method. Seems to me that a DSSSL stylesheet:

* uses primitive objects defined by the DSSSL standard and implemented 
in the DSSSL engine (Jade or whatever)

* possibly defines higher-level objects based on those primitives

* defines and implements methods for representing SGML elements
... which is the main point for most people.

... or am I not understanding the meaning of object and method?

 > Another application would be to have a browser display stylesheet for
 > HTML, and a print style sheet for the same html.dtd.

Note the "would be." This usefulness of this excellent idea depends, of 
course, on the browser-makers supporting it. And given their
half-hearted support for the very simple CSS standard, DSSSL support
may be too much to hope for in our lifetimes.

Speaking of which, does anybody know if Mozilla/Netscape 5.0 supports
CSS any better than 4.0?

Matt Gushee
Oshamanbe, Hokkaido
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