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Re: Issue 163, was: Meaning of invalid but well-formed dates

From: Dan Winship <dan.winship@gmail.com>
Date: Mon, 18 May 2009 15:28:45 -0400
Message-ID: <4A11B6ED.6020801@gmail.com>
To: Julian Reschke <julian.reschke@gmx.de>
CC: Brian Smith <brian@briansmith.org>, 'HTTP Working Group' <ietf-http-wg@w3.org>
Julian Reschke wrote:
> Yes, the 2-digit dates are a can of worms. This is a mess, we do both
> say "MUST accept", but then do not say what it means.

And we *can't* just assert a meaning arbitrarily, since we also forbid
implementations to send them, and so by definition, if you receive an
rfc850-date, then you've received it from an implementation that doesn't
obey our rules...

> That being said, changing a normative requirement from RFC2616, even if
> it's underspecified, is something we shouldn't do lightly.

Has anyone even seen an rfc850-date in the wild recently?

Anyway, if you really want to nail their semantics down, RFC 2616 and
1945 (HTTP/1.0) both say that the Date header has "the same semantics as
orig-date in RFC 822", and RFC 822 says that "If included, day-of-week
must be the day implied by the date specification." Since HTTP's
rfc850-date syntax requires the day of week to be present, then if we
just say implementations SHOULD assume all rfc850-dates refer to years
between 1900 and 2299, then they are no longer ambiguous, merely
annoying. "Monday, 18-May-09 19:16:46 GMT" is today, and "Tuesday,
18-May-09 19:16:46 GMT" was 100 years ago.

-- Dan
Received on Monday, 18 May 2009 19:29:22 UTC

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