[OpenISO] Problems with the "combined date and time representation"

[Henrik Sundberg]

I fully agree with the text, but shouldn't a heading for proposed
solution be added?
/$

2007/12/30, Norbert Bollow <nb at bollow.ch>:
> Here is some draft text for the "OpenISO.org Problem Report about OOXML"
> document.
>
> Please comment on this... do you think that this is a useful format?
>
> (I think we shouldn't discuss all issues in this format, only those
> that we expect to cause serious problems of some kind unless
> appropriately addressed.)
>
>
> --snip---------------------------------------------------------------
>
> Timezone information for spreadsheet date-and-time data
> =======================================================
>
> Part 4, 3.17.4.2 and 3.17.6.7
>
> Problem description:
> ~~~~~~~~~~~~~~~~~~~~
>
> The numeric data format for date information in OOXML's spreadsheet
> data format, the so-called "combined date and time representation",
> has undefined semantics with regard to what timezone the date-and-time
> data refers to.
>
> Expected impact:
> ~~~~~~~~~~~~~~~~
>
> Unless this issue is fixed in the specification, serious
> interoperability problems are to be expected whenever date-and-time
> data is communicated timezone boundaries.
>
> In the internet age, as more and more business processes are
> coordinated and integrated internationally, it is clearly a
> requirement that information must remain valid when it is
> communicated across timezone boundaries.
>
>
>
> The switch to daylight-saving time and back
> ===========================================
>
> Part 4, 3.17.4.3
>
> Problem description:
> ~~~~~~~~~~~~~~~~~~~~
>
> The numeric data format for date information in OOXML's spreadsheet
> data format, the so-called "combined date and time representation",
> represents times as fractional days, with the assumption that each
> day has 24 hours.
>
> Expected impact:
> ~~~~~~~~~~~~~~~~
>
> Unless this issue is fixed in the specification, serious
> interoperability problems are to be expected with regard to time data
> concerning days on which the switch to daylight-saving time or back
> occurs.
>
> The interoperability problem consists in the introduction of errors
> of up to one hour for each affected time value, and it is particularly
> problematic because the issue can easily be overlooked during testing.
>
>
>
> Dates before March 1, 1900
> ==========================
>
> Part 3, 3.16.9
> Part 4, 3.17.4.1
>
> Problem description:
> ~~~~~~~~~~~~~~~~~~~~
>
> The numeric data format for date information in OOXML's spreadsheet
> data format, the so-called "combined date and time representation",
> does not allow to correctly represent dates before March 1, 1900.
> (Dates before January 1, 1900 cannot be preseneted at all.  Dates
> from January 1, 1900 until February 28, 1900 are affected by the
> so-called "leap year bug" which consists in the "combined date and
> time representation" assigning a day number to the non-exiting day
> "February 29, 1900" even though the year 1900 was not a leap year.
> In addition, the draft standard specifies the following behavior
> for the WEEKDAY function: "for dates between January 1 and February
> 28, WEEKDAY shall return a value for the day immediately prior to the
> correct day".)
>
> Expected impact:
> ~~~~~~~~~~~~~~~~
>
> Unless this issue is fixed in the specification, serious
> interoperability problems are to be expected whenever information
> about dates before March 1, 1900 is exchanged by different programs.
>
> Historical studies often consider dates before 1900.  Also, there are
> people alive today who were born before 1900.
> --snap---------------------------------------------------------------
>
>
> Greetings,
> Norbert.
>
>
> --
> Norbert Bollow <nb at bollow.ch>                      http://Norbert.ch
> President of the Swiss Internet User Group SIUG    http://SIUG.ch
> Working on establishing a non-corrupt and
> truly /open/ international standards organization  http://OpenISO.org
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