🚀 go-pugleaf

In article <555@helios.prosys.se>, ath@prosys.se (Anders Thulin) writes:
> I've been trying to make sense of the SGML standard. I'm beginning to
> think that it shouldn't be done at home, and only attempted by highly
> trained professionals :-,

<flame>
It shouldn't be done at all.  The SGML standard is, without a doubt,
the poorest excuse for a language standard I have ever seen.  I can
only assume that it was developed by people with no knowledge of
formal languages who adopted a formalism to make the resulting
document look more technical.  Regular expressions are clearly
inappropriate for describing the language, a phrase structure grammar
would have been much better.  In addition, the standard contains a
number of errors, inconsistencies, ambiguities, and violations of
the formalisms.  The SGML standard is in dire need of interpretation
and revision -- unfortunately, unlike ANSI standards which clearly
specify how to go about submitting comments and requesting
interpretations, ISO standards provide no clues at all.
</flame>

Now, having gotten that out of my system, allow me to try to provide
some answers to your questions.

> This is my problem.  Section 9.6.1 seem to be very clear on the extent
> on CON mode: it's essentially used `inside' the _content_ production
> [27].  How, then, are delimiters *outside* _content_ recognized?

That's what it says, but it's not what it means.  CON mode is simply
the default mode when you're not in any other mode.  So you do indeed
start off at the very beginning of the entire document in CON mode
and return to it whenever a nested mode is ended.

> Another problem is the ">" delimiter. According to the table in Figure
> 3 (page 31) in the standard, ">" is recognized as either MDC or TAGC
> in CTX mode. But I find nothing that says why it should be recognized
> as one rather than the other.

CXT isn't a real mode, it's just a pseudo-mode.  Some delimiters
aren't recognized as such unless they are followed by some particular
context as sepcified in 9.6.2.  This context may include other
delimiters so CXT mode is used to indicate that a delimiter needs to
be recognize while verifying the context of another delimiter.  Thus,
there should really be a separate CXT mode for each of the contexts
listed in 9.6.2 (e.g. DCL-CXT, GI-CXT, etc.) and the table in Figure
3 should be expanded appropriately (e.g. TAGC should be GI-CXT [but
only if "SHORTTAG YES" is specified on the SGML declaration], and
MDC should be DCL-CXT and MSE-CXT).
----
Larry Jones                         UUCP: uunet!sdrc!thor!scjones
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