-00:00 on draft-newman-datetime-00.txt

[Paul Eggert]

   Date: Thu, 02 Jan 1997 16:45:07 -0500
   From: kuhn at cs.purdue.edu ("Markus G. Kuhn")

   > Section 4.2
   > 
   >   When the local offset is unknown, the offset "-00:00" MAY be used to
   >   indicate that the time is in UTC and the local offset is unknown.
   > 
   > This is worded a little confusingly -- could you please clarify? ....

   On board a plane, in orbit, in a submarine, in any mobile
   device that receives time only by GPS or NTP, in my labtop that I carry
   with me during my next south pole tour, ...

I should have stated my question more clearly.  In some cases, local
time may be defined but not known (e.g. a UTC-based timepiece at an
unknown location); in other cases, local time itself may be undefined
(an extreme example of this is the North Pole; there are other, more
common, examples, e.g. aircraft flying over most of the Pacific, where
there is no established convention for time zone boundaries or for
whether daylight saving applies).  I couldn't tell which case was
intended from the original wording; I now see from other people's
responses that the former was undoubtedly intended but it might be
helpful to clarify the wording here.

While we're on the subject, I think `-00:00' is a kludge and should be
removed.  How about the following convention instead?

 `Z' means the time is in UTC and the local UTC offset is unknown or undefined.
 `+00' means the time is in UTC and the local UTC offset is 0.

This conveys the same information as the convention proposed in
section 4.2 of draft-newman-datetime-00.txt, but it's easier to
explain and is more consistent.