[Bug 6046] Why does range of legal time zone offsets exceed actual usage?

http://www.w3.org/Bugs/Public/show_bug.cgi?id=6046


C. M. Sperberg-McQueen <cmsmcq@w3.org> changed:

           What    |Removed                     |Added
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             Status|NEW                         |ASSIGNED




--- Comment #1 from C. M. Sperberg-McQueen <cmsmcq@w3.org>  2008-09-09 02:57:15 ---
Thanks for the comment.

In setting the upper and lower bounds for the time zone offset portion
of the seven-property model, the XML Schema WG was motivated to provide
a little extra room, going beyond current usage, in order to ensure that
the type would not need to be redefined if some jurisdiction chose to
change the offset of its civic time to UTC.  If memory serves, this happened
as recently as 1999, when some jurisdictions in the Pacific vied to be
the first inhabited bits of land to see the new millennium come.

Note that the definition of the type over-generates here in another way,
as well:  it allows for offsets of arbitrary numbers of minutes, even 
though almost all jurisdictions define civil time in terms of an integral
number of hours offset from UTC, a few using half-hours, and only one that
I know of using an offset which is on the UTC quarter-hour.  Any sanity
check that seeks to ensure that the offset given is an offset actually in
use will need to do more than restrict the upper bound.

Speaking for myself, I am a bit concerned that the upper and lower bounds
on the type don't give more breathing room for further changes of this sort.
But compatibility issues will make it difficult to change the bounds, in 
any case.


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Received on Tuesday, 9 September 2008 02:57:48 UTC