[whatwg] Historic dates in HTML5

Andy Mabbett andy at pigsonthewing.org.uk
Thu Mar 5 12:19:17 PST 2009

In message <10C0368B-E984-42A7-933F-B7CB6F1F2B0E at iki.fi>, Henri Sivonen 
<hsivonen at iki.fi> writes

>On Mar 5, 2009, at 01:29, Jim O'Donnell wrote:
>> Is there any suitable markup in HTML5 for dates in digitised 
>>documents from museums, libraries and archives?
>What would consuming software do with those dates?

I have already described some of the many use-cases for such dates, in:


et seq.

>The <time> element is meant as a replacement for the microformat
><abbr> design pattern in hCalendar

Is it? What about the other abuses of ABBR in microformats, such as for 
coordinates and duration:

         <abbr class="duration" title="PT5M48S">5:48</abbr> ?

>(if the microformat community  embraces <time>; if not, <time> in pretty
 >much pointless in HTML5).

What about the use-cases which I have described, most of which are not 
dependent on microformats?

>The expected use cases of hCalendar are mainly transferring *future*
>event entries from a Web page into an application like iCal.

Are they? Could you provide a citation for that?

The hCalendar spec doesn't include a definitive set of use-cases 
(indeed, hardly any at all - but then it doesn't even include a full set 
of hCalendar parameters), but it does explicitly refer to "writeups of 
past events".

Many of the hCalendar microformats which I've seen published are for 
historic events, such as those on Wikipedia, for example:

         Launch of Sputnik 1:

         Marriage Act, 1753:

Are you suggesting that they are in some way in breach of the hCalendar 
spec? If so, how??

You also seem to overlook that dates are not used not only in hCalendar, 
but also in other microformats, such as hAtom (for dating feeds) , and 
hCard (for people's birth dates), for example:

         Sir Tim Berners-Lee:

         Anthony of Saxony:

The only limit on the use of dates in microformats is that they 
currently rely on ISO8601, which is restricted to Gregorian dates 
(chiefly after 1750, but see:


for the complex change-over dates in different countries). This was 
identified as an issue with the hCalendar specification in September 


and is still awaiting a solution, hence my proposal for allowing 
non-Gregorian dates in <time> (at the first URL given above).

Andy Mabbett

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