Date: Mon, 10 Jun 1991 18:35:38 -0400 (EDT)
From: Nathaniel Borenstein <nsb>
Subject: Re: I vote NO to Richmail
I guess I had been thinking of richmail's lack of syntactic conformance
to anything else as a virtue rather than a problem, because it avoids
religious wars such as ODA vs. SGML vs. RTF vs. whatever. That is, if a
rich mail format is syntactically compatible with one of the above,
doesn't promoting its use imply a preference for the one it conforms
with? One of my goals with richmail was to make "richer" text
available *without* having to get involved in those wars...
As someone who worked for several years with ODA & knows a fair amount
about SGML, let me wade right into this one.
The religious war between ODA & SGML hs always struck me as silly,
because ODA & SGML are incomparable. ODA is a document architecture
that defines both a syntax (actually 2) & a complete semantics. As
such, it is basically not extensible (i.e., you can not add your own new
kinds of "things" to it, like arbitrary hypertext annotations).
SGML on the other hand is almost exactly the opposite. SGML is ONLY a
syntax with no semantics (actually, SGML does define a semantics, but
the semantics only involves how the SGML is to be parsed,essentially).
SGML is completely extensible. If you want to get semantics with SGML,
you must define the semantics yourself, by defining what the various
symbols "mean". E.g., you would say something like, "the tag
`paragraph' indicates the ocurrence of a pargarph, which is to be
formatted ...". The label `paragraph' means nothing to SGML.
In fact, one of the allowable syntaxes for ODA is SGML.
The bottom line is that using SGML would buy you adherence to an
international standard without having to buy into anyone's document
semantics. Except for the complexity of defining a legal "SGML
application", going with SGML may be a fine idea. (An "SGML application"
is a technical term defined by the standard. The application consist of
several pieces, among them: a rigorous definition, expressed in SGML, of
the subset of SGML you will be using; some text describing the "meaning"
of the tags you will be using; a Doument Type Definition, which defines
the SGML strings that are legal in your subset. An application is
tricky to define unless you are an SGML expert. I ain't.)
Another comment: what you need for a richmail format is so simple that
it would be absoultely insane to consider something as complicated as