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Re: [whatwg] <time>

From: Leif Halvard Silli <lhs@malform.no>
Date: Thu, 12 Mar 2009 18:38:08 +0100
Message-ID: <49B94880.4090500@malform.no>
To: Lachlan Hunt <lachlan.hunt@lachy.id.au>
CC: David Singer <singer@apple.com>, whatwg@lists.whatwg.org, "public-html@w3.org" <public-html@w3.org>
Lachlan Hunt 2009-03-12 12.35:

[ "real problems" linked to hCalendar: ]

> e.g. the date 04/02/09 means different things to different people
> depending on the conventions used in their country. By using the time
> element <time datetime="2009-02-04">04/02/09</time>, the ambiguity can
> be solved by allowing UAs to expose the date to the user in a less
> ambiguous format.  (Although, it would be better if people avoided such 
> ambiguous dates, that doesn't seem too likely to happen with most people).

If the purpose of @datatime is to be able to expose the ambiguous 
date to the user, then what is the advantage of using @datetime 
instead of @title? After all, @title is what is used in <abbr>?!

If the focus is on exposing ambiguous dates, then what is the 
purpose of limiting it to proleptic Gregorian dates? For example 
the battle of Hastings (16th of October 1066 - according to the 
Julian calendar [1]). It would only be confusing to expose that 
date to some users - e.g. to AT users - in the proleptic Gregorian 
date format.

If the purpose is exposing ambiguous dates, it would also not hurt 
anyone in need of unambiguous date information, to simply ignore 
the fact that @datetime - as drafted - is supposed to contain 
proleptic Gregorian dates. Simply using <time 
datetime="1066-10-16">October 16th</time> would bring the expected 
user experience.

Clearly, from the hCalendar use case you have outlined here, it 
isn't necesary to limit @datetime to proleptic Gregorian dates. 
However, from the same angle it also isn't necessary to add 
calendar information. The only thing that is needed is to offer 
the date in a syntax that makes the ambigious date read in a way 
that is unambigious to the user. The user will simply have to find 
out the calender used by other means.

Clearly, if exposing ambiguous dates (= the hCalendar usecase ?) 
is the basis for @datetime, then there is no congruency between 
the requirement of a proleptic Gregorian date and the usecase.

> Another potential problem solved is helping to distinguish arbitrary 4 
> digit numbers from years, so that screen readers can pronounce them 
> correctly. e.g. If 1983 is meant as just a number, it should be 
> pronounced as "one thousand nine hundred and eighty three". But if it's 
> meant as a year, then it's conventional to say "nineteen eighty three" 
> instead.  Although, I'm not certain if this is a real problem or not, I 
> could be completely wrong about this.  I've been told that screen 
> readers have settings for this and possibly some limited heuristics for 
> detecting if a given number is a year or not.

This use case doesn't involve the @datetime attribute. It *could* 
have involve a @calendar attribute, however. (Or even @datetime, 
if it was permitted to use it for calendar information in it. )

> [1] http://en.wikipedia.org/wiki/ISO_8601#Durations
> [2] http://dev.w3.org/html5/html-design-principles/#solve-real-problems
> [3] 
> http://esw.w3.org/topic/HTML/DesignPrinciplesReview#head-98fea741b3ace0c8da87029864ec4a5db4b2358e 

[1] http://en.wikipedia.org/wiki/Battle_of_Hastings
leif halvard silli
Received on Thursday, 12 March 2009 17:38:53 UTC

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