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1819Re: Wow, no posts for a long time

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  • piebaldconsult
    Sep 14, 2006
      > [a] In the notation of a time interval by its start and end,
      > is there any requirement that the end shall not be
      > before the start?

      No, none that I can see.

      >Can a time interval be empty?

      No, in :2004 it's section which is the same as :2000 section

      "... combining any two complete date and time of day
      representations ..."

      > [b] While [ISO 8601:2004] has removed the concept of "truncated"
      > notations, they still seem to allow the omission of "higher
      > order time elements" in the notation of the end point of a
      > time interval given by its start and end. There is no syntax
      > for such omissions, so it is not clear what can be omitted,
      > and which separators must be written. Which of the following
      > are allowed:
      > 2006-09-07/08
      > 2006-09-07/-08
      > 2006-09-07/07-09-07 -- is century a "time element"?
      > 2006-09-07/T12 -- for 2006-09-07/2006-09-07T12
      > 2006-w36-4/-251 -- for 2006-w36-4/2006-251
      > 2006-w36-4/251 -- for 2006-w36-4/2006-251

      These are in :2004 section 4.4.5 which is the same as :2005 5.5.5

      And "Mutual agreement" is required here. However, I would not use any
      of the "incomplete" representations. They seem to me to be more
      useful to human-readability and less useful to computer-
      understandability. The computer doesn't mind reading and writing a
      few more bytes.

      > [c] By "mutual agreement", a duration can be given as eg
      > P0001-02-03
      > to indicate "1 year + 2 months + 3 days". This would allow
      > P-0001-02-03
      > but what does it mean? "durations" must not be negative
      > in [ISO 8601:2004].

      Hmmm... no, the standard says "PYYYY ..." , not "P+-YYYY ..."

      > [d] A Note to the definition of "duration" says that leap seconds
      > must be "accounted" for in the length of epoch intervals.
      > Even though Notes are not normative, does this mean that
      > the end point of
      > 2005-12-31T12Z/P1D
      > shall be 2006-01-01T11:59:59Z rather than 2006-01-
      > (A leap second occured at 2005-12-31T23:59:60Z.)

      Unclear in :2000, :2004 is better, section 2.2.7 says

      <duration> duration of a calender day

      NOTE The term "day" applies also to the duration of any time interval
      which starts at a certain time of day at a certain calendar day and
      ends at the same time of day at the next calendar day.

      So I wouldn't worry about them.
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