[whatwg] [wf2] Leap seconds, dates in the past

[Henri Sivonen]

Earlier I raised the issue that WF 2.0 does not say what should be  
done about leap seconds, but I did not suggest a solution. Having  
read more about the subject, I suggest that date calculations in WF  
2.0 be POSIXly correct and ignore leap seconds. (See IEEE 1003.1,  
2004 Edition, section 4.14 Seconds Since the Epoch or the  
corresponding section in ISO/IEC 9945-1.)

Another problem I see is that ISO 8601 leaves wiggle room with dates  
that predate the use of the Gregorian calendar. I think there are  
three politically correct ways of approaching this:
  1) Mandating the use of the proleptic Gregorian calendar all the  
way to 0001-01-01.
  2) Prohibiting dates before 1924-01-01. (By that time, all  
countries that previously used the Julian calendar had upgraded to  
the Gregorian calendar for non-religious purposes, according to  
Wikipedia.)
  3) Require the change from Julian to Gregorian between 1582-10-4  
and 1582-10-15. (Dates from Wikipedia--caveat lector.) This is the  
ICU default behavior, BTW.

The politically incorrect way that comes to mind is what the Unix cal  
utility does: Following the British Julian to Gregorian upgrade. (Run  
the command 'cal 9 1752' on a *nix system to see what I mean.)

I'm inclined to think that the best option for WF 2.0 is to require  
the use of the proleptic Gregorian calendar all the way to 0001-01-01.

-- 
Henri Sivonen
hsivonen at iki.fi
http://hsivonen.iki.fi/