"G. Adam Stanislav" wrote on 1999-06-26 18:34 UTC:
> Can someone tell me if there is an international standard declaring what the
> first day of the week is?
ISO 8601 numbers the days of the week from Monday = 1 to Sunday = 7.
ISO 8601 also numbers the weeks within a year. Week 1 of a year is the
first week that has at least 4 days in January. This is equivalent to
the week that contains the first Thursday of a new year. The seven days
before week 1 always belong to week 52 or week 53 of the previous year
There is no week 0. The year of the current day and the year of the
current week can consequently be different in the first or last three
days of a year, because week and year boundaries are not necessarily
aligned.
More details and a pointer to a copy of the full standard and a draft of
the 1999 revision are on:
http://www.cl.cam.ac.uk/~mgk25/iso-time.html
ISO week numbers are pretty widely used in many countries in Europe,
especially for industrial planning purposes. You will frequently hear
things like "We will deliver in week 14" in Swedish or German companies.
In pocket calendars and organizers that have one week per page, the ISO
week number and its year together form a standard calendar page number,
to which people can conveniently refer.
US calendars seem to start the week predominantly at Sunday, only some
business organizers and calendars use the ISO week scheme as well. I
have not yet found any more formal reference for why they start weeks at
Sunday. It seems to be more a custom than a standard. Week numbers are
also not widely used in the US and the only "formal" US week number spec
that I have ever seen is the strange %W value in C's strftime(), which
funnily starts the week with Monday while %w starts with Sunday=0.
ISO C 9x drafts contain ISO 8601 week numbers in strftime(), for details
see <http://www.cl.cam.ac.uk/~mgk25/c-time/>.
Today is day 6 of week 25 of the year 1999, short 1999-W25-6, equivalent
to Saturday, 1999-06-26. In the US, people would probably say "the week
of June 26" instead of the European "week 25".
Hope this helped ...
Markus
-- Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
This archive was generated by hypermail 2.1.2 : Tue Jul 10 2001 - 17:20:47 EDT