[whatwg] <time>

[Charles McCathieNevile]

On Mon, 09 Mar 2009 21:17:01 +0100, Tom Duhamel <tom420.duhamel at gmail.com>  
wrote:


> Precise Date/Time
>
> My understanding is that the current protocol will only accept this  
> format for a valid precise date:
> 2009-03-09
> And this format for a valid precise time:
> 15:10 or 15:10:19
>
> My opinion is that all the following dates are precise:
> 2009
> 2009-03
> 2009-03-09

I agree. These are also acceptable with ISO-8601 (although to be honest  
that spec accepts so many things it isn't always a good reference) and I  
think they are indeed useful things to be able to say about the future.

> Gregorian Calendar
>
> There have been requests that the <time> element accepts dates expressed  
> in other calendars than Gregorian. This is not doable, although I do  
> understand those who mentioned this, mostly about the Julian calendar.
>
> Julian for instance cannot give a precise date (we are not considering  
> the fact that it was not precise enough) because it was based on some
> events in history, often the arrival of a new leader. For example,
> when Bush was elected in Nov 2000, we would have considered that year
> to be the new year 1. Thus Bush was elected in November 1, re-elected
> in November 5. Then Obama was elected in November 9 of the Bush era,
> which was also Novemember 1 of Obama era.

This is not correct. (I am, as it happens, an historian who works at  
something else :) ). The Julian calendar only came into being in about  
45BCE, and leap years were a bit odd until about 40 years later. For Roman  
calendars before the Julian calendar there is pretty good evidence,  
although they were named for the consuls elected that year. I.e. years  
were generally known by a pair of names rather than a number, but you can  
go back a long way with those names.

> Wikipedia is often mentioned as a use-case, but based on my own  
> experience (I am not an historian or anything, so my use of
> Wikipedia for historical events is sporadic) they most usually
> convert Julian dates to the Gregorian calendar. Julius Caesar
> died in 14 BC, not 52 of the Julius era on the Julian calendar
> (or whatever date it would convert to).

Nope, you are confusing your calendars here. The Gregorian and Julian  
calendars look the same, but 3 times every 400 years the Gregorian  
calendar skips a leap year that would have occurred in the Julian one. So  
Wikipedia dates are generally (but not always) Julian.

What does happen is that Roman years were still named for consuls - the  
convention of using the supposed birth of Jesus as the year 1 came a few  
centuries later. So the "50 BC" bit in Asterix would have been called "the  
year of the consuls L. Aemilius Lepidus Paullus C. Claudius Marcellus" at  
the time - and the year 100 AD would have been called something similar.  
The reason why we count back so many years is because we have very good  
records that make it easy to turn the named years into numbers (for people  
who didn't go to a Roman school and get beaten until they could recite the  
names of consuls for a few centuries), and can easily date lots of events  
(but not the birth of Jesus, which probably took place around 4-6 BC :) ).

cheers

Chaals

-- 
Charles McCathieNevile  Opera Software, Standards Group
     je parle français -- hablo español -- jeg lærer norsk
http://my.opera.com/chaals       Try Opera: http://www.opera.com