[whatwg] <time>

Mikko Rantalainen mikko.rantalainen at peda.net
Mon Mar 16 06:49:54 PDT 2009

Smylers wrote:
> Robert J Burns writes:
>> Right now we have a draft that: 2) allows 0000 without attaching
>> sufficient meaning to it
> I don't think that's the case; the algorithm for parsing a year requires
> a number "greater than zero":
>   http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#parse-a-month-component
> So my suggestion for a spec change is to replace "zero" with "1582".
> That further reduces the set of dates that <time> can represent, but
> avoids the complexity of pre-Gregorian dates, and avoids inadvertently
> giving a meaning to them that hampers the efforts of a future version of
> HTML to do all of this right.

Just remove the rule "If year is not a number greater than zero, then fail."

The objective, if I've understood correctly, is to be able to markup a
specific time. Proleptic Gregorian calendar is suitable for specifying a
moment of time before 1582 without a doubt. The only thing that must be
*exclicitly* defined is whether or not the day before 0001-01-01 is
0000-12-31 or not. I think that it should be. If it is, it immediately
follows that year "-6" is same as "7 BC" and I cannot see any problem
with that. The "BC" is different unit so there can (and should) be an
offset compared to unitless year number.

If you cannot accept Proleptic Gregorian calendar because you believe
that it cannot be defined exactly enough, then another possible choice
would be the POSIX time (number of seconds since 1970-01-01 00:00:00
UTC). Make that floating point number with arbitrary precision and it
can specify any moment in the history or in the future. If less than one
second precision is needed, require author to always specify range in
that case. Really simple to implement and definitely exact enough.

Different calendar systems and daylight saving times are only methods
for displaying or describing specific moments of time. The only thing
required for HTML is *a method* for marking up any specific moment of
time. I repeat: primary objective is to markup any specific moment and
secondary objective is to make markup easy enough for the authors (I
believe that the unix timestamp is not acceptable because it cannot be
authored without using software aids). I do not believe that marking up
a given moment with multiple different methods should be an objective.


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