New Last Call: 'Tags for Identifying Languages' to BCP

Bruce Lilly blilly at
Sun Dec 12 18:16:33 CET 2004

>  Date: 2004-12-11 00:52
>  From: "Mark Davis" <mark.davis at>
>  To: ietf-languages at, ietf at
>  CC: ietf at
> > The ABNF is an expression of the grammar that
> describes the set of all valid tags.
> No, this is simply incorrect. You cannot expect that any implementation that
> simply does the ABNF is conformant.

I made no such claim.  I do claim that if the ABNF
contradicts the normative text, as is the case in
your draft w.r.t. acceptance of several constructs
not permitted by RFC 3066 ABNF, that there is an
error in either the normative text or the ABNF.

> There are a great many constraints on 
> the tags that are not in the ABNF grammar, that are clearly required in any
> reading of the text. Most of these *cannot* be encompassed in any ABNF
> grammar.

If your claim is that the ABNF cannot express a
grammar consistent with the RFC 3066 ABNF, that
is clearly false.

> There are a few that could be expressed in the ABNF; some at little 
> cost, some with a great deal of complication.

Are you claiming that it is unduly difficult to
make the ABNF match RFC 3066's?

> This is not a technical 
> problem for the draft.

It is a problem due to the conflict between the
ABNF and the text.  It is a problem because it
opens a loophole for future revisions to formalize
content which is incompatible with RFC 3066
> > as reasonable as the current worst-case of 11 octets.
> Also simply untrue. You seem not to be reading all the messages on this
> subject. Look at the ABNF for RFC 3066. There is *no* limit in the ABNF
> there!

The draft proposes closing RFC 3066-style registrations.
Show me a registered RFC 3066 language tag longer than
11 octets.  Show me a general-use (i.e. not private-use)
RFC 3066 language tag which is too long to be used in an
RFC 2047/2231 encoded-word.  Show me a general-use RFC
3066 language tag which is too long to fit on an RFC
2822/3282 Content-Language header field line.

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