Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consensus call
John C Klensin <john-ietf@jck.com> Fri, 18 May 2007 14:03 UTC
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Date: Fri, 18 May 2007 10:03:31 -0400
From: John C Klensin <john-ietf@jck.com>
To: Tony Finch <dot@dotat.at>
Subject: Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consensus call
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--On Friday, 18 May, 2007 09:00 +0100 Tony Finch <dot@dotat.at> wrote: > On Thu, 17 May 2007, John C Klensin wrote: >> >> After all <CRLF> Thing <SPACE><CRLF> could case similar >> problems if some construction permitted it ... > > This is not news. There have for a long time been problems with > significant trailing space, which is why CRLF 1*WSP CRLF in a > header is part of the obs- syntax of 2822, and why > quoted-printable encodes WSP at the end of a line. > >> ... and defining a grammar that would prohibit any >> <SPACE><CRLF> construction isn't easy in ABNF for reasons >> that have nothing to do with LWSP. > > This is simply incorrect. It's trivial to define a whitespace > construction that only allows CRLF at the beginning of a > sequence: > > NTWSP = [CRLF] 1*WSP ; non-trailing white space Sure. Except that much, if not most, of our textual descriptions of these protocols describes lines, and line-like, constructions as _ending_ in CRLF. Moving to "starting in CRLF" creates a conceptual difference between prose definition and formal syntax, which strikes me as a bad idea. Of course, in the above, since [CRLF] is optional, "1*WSP" alone satisfies the production as written and still does not prevent <CRLF> space space space <CRLF> unless _all_ productions are written CRLF first... or one relies on the comment as a restriction. And a comment as the restriction --in the prose-- is exactly what has been suggested, IMO. john
- Use of LWSP in ABNF -- consensus call Lisa Dusseault
- Re: Use of LWSP in ABNF -- consensus call Julian Reschke
- Re: Use of LWSP in ABNF -- consensus call Frank Ellermann
- Re: Use of LWSP in ABNF -- consensus call Lisa Dusseault
- Re: Use of LWSP in ABNF -- consensus call Paul Hoffman
- Re: Use of LWSP in ABNF -- consensus call Tony Hansen
- Re: Use of LWSP in ABNF -- consensus call Tony Finch
- Re: Use of LWSP in ABNF -- consensus call Clive D.W. Feather
- Re: Use of LWSP in ABNF -- consensus call Keith Moore
- Re: Use of LWSP in ABNF -- consensus call Harald Alvestrand
- Re: Use of LWSP in ABNF -- consensus call Frank Ellermann
- Re: Use of LWSP in ABNF -- consensus call Ned Freed
- Re: Use of LWSP in ABNF -- consensus call John C Klensin
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Tony Finch
- Re: Use of LWSP in ABNF -- consensus call Dave Crocker
- Re: Use of LWSP in ABNF -- consensus call Eric Allman
- Re: Use of LWSP in ABNF -- consensus call Philip Guenther
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Dave Crocker
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Dave Crocker
- Re: Use of LWSP in ABNF -- consensus call Douglas Otis
- Re: Use of LWSP in ABNF -- consensus call Alexey Melnikov
- RE: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Bill.Oxley
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… John C Klensin
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… John C Klensin
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Tony Finch
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… John C Klensin
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Harald Tveit Alvestrand
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Dave Crocker
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… todd glassey
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Sam Hartman
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Sam Hartman
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Dave Crocker
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Tony Finch
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… John C Klensin
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Keith Moore
- Re: Use of LWSP in ABNF -- consensus call Frank Ellermann
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Tony Finch
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Sam Hartman
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Sam Hartman
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… John C Klensin
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Tony Finch
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Sam Hartman
- Re: Use of LWSP in ABNF -- consensus call Lisa Dusseault
- Re: [ietf-dkim] Re: Use of LWSP in ABNF -- consen… Clive D.W. Feather
- Re: Use of LWSP in ABNF -- consensus call Lisa Dusseault
- Re: Use of LWSP in ABNF -- consensus call Dave Crocker
- Re: Use of LWSP in ABNF -- consensus call Keith Moore
- Re: Use of LWSP in ABNF -- consensus call Frank Ellermann
- Re: Use of LWSP in ABNF -- consensus call John C Klensin
- Re: Use of LWSP in ABNF -- consensus call Alexey Melnikov
- Re: Use of LWSP in ABNF -- consensus call Clive D.W. Feather
- Re: Use of LWSP in ABNF -- consensus call Dave Crocker