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Re: <time> values in HTML5

From: John Cowan <cowan@mercury.ccil.org>
Date: Sat, 3 Dec 2011 15:18:40 -0500
To: Toby Inkster <tai@g5n.co.uk>
Cc: tantek@cs.stanford.edu, John Cowan <cowan@ccil.org>, Jeni Tennison <jeni@jenitennison.com>, www-xml-schema-comments@w3.org, HTML Data Task Force WG <public-html-data-tf@w3.org>, RDFa WG <public-rdfa-wg@w3.org>, public-html-xml@w3.org
Message-ID: <20111203201840.GB8325@mercury.ccil.org>
Toby Inkster scripsit:

> ISO 8601 gives us a nice, standard notation for durations. I'd support
> subsetting it if there were massive disadvantages to adopting the
> full notation, but I don't think these disadvantages exist. I've
> written a parser for ISO 8601 durations before, and I can't recall
> the requirement to differentiate between 'M' before and after the 'T'
> being especially onerous to implement.

I presume what's under discussion is the XML Schema subset of 8601,
which excludes duration in weeks (these take the form PnW meaning "n
7-day weeks").  I'm not sure why these were excluded.

Note that contrary to what XML Schema Part 2 says, the underlying value
space of a duration is two-dimensional: months and seconds.  We need two
because the number of seconds in a month depends on what month it is,
whereas years can be reliably reduced to months, and days/hours/minutes
can be reliably reduced to seconds (given that XML Schema does not permit
talk of leap seconds).  XML Schema 1.1 gets this right.

-- 
By Elbereth and Luthien the Fair, you shall     cowan@ccil.org
have neither the Ring nor me!  --Frodo          http://www.ccil.org/~cowan
Received on Saturday, 3 December 2011 20:19:15 GMT

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