Subject: RE: RFC 2445 contradiction

From: [email-masked]
Date: Fri, 9 Feb 2001 12:55:26 -0600

> But, unless otherwise marked, all text in an RFC is 
> normative, so that both the
> prose and the ABNF specify the standard.  That's redundancy.

Redundant is the wrong word. They are complementary. Certainly, we want both
a machine processable and a human readable description of the specifications
in the IETF. Hence, the use of a standard ABNF and also the prose.

Redundant implies you can remove one or the other. They are not redundant.
Yes, they are both normative. But the introduction is clear that in cases of
discrepancy, the ABNF rules. And our responsibility is to correct any such
errors so that they two align properly.

---

From: John Stracke <[email-masked]>
Date: Fri, 09 Feb 2001 14:24:07 -0500

[email-masked] wrote:

> Redundant is the wrong word. They are complementary.

But, at the moment, they're in contradiction, right? And the only way that can
happen is if they cover the same topic; i.e., they're redundant.  And that's
why redundancy in a spec is risky: you can get different answers depending on
which section you're looking at.

> Certainly, we want both
> in the IETF.

I'm not so sure.  Another approach would be to have a formal definition of the
syntax, with a prose definition of the semantics.  The prose would reference
the formal definition, but would not duplicate it.

(I prefer to think of it as "formal" rather than "machine processable" because,
commonly, parser generators don't accept ABNF as such, and wouldn't do much
useful if it if they did--with lex/yacc, for example, you usually need to
intermingle C code into your grammar.)

This is all theoretical, of course; the approach that was actually taken is
certainly Good Enough, and I definitely don't advocate wholesale rewriting at
this late date--we might theoretically fix some bugs, but we'd almost certainly
end up introducing new ones.

--
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