ISO-8601, Swedes, Standards, Related

Swedes uses international standard for date and time representations. (See also SI for units.)

To set the record straight...:

Dates are written on format:

YYYY-MM-DD

Time of the day is written
using 24-hour system:

hh:mm:ss

The week starts with Monday.
(Not Sunday, or Saturday, or anything else)

Week numbering is a great practice and
first week on the year, week 1,
is the week that contains first Thursday
of the new year, equiv. to Jan 4th

From Numeric representation of Dates and Time The ISO solution to a long-standing source of confusion.

Format	Who Uses
YYYY-MM-DD (& hh:mm:dd 24-hr system)	(International standard) Sweden, Japan, China + scientists, Swedes, and other really smart people around the whole world; computers, Internet (RFC-3339). *Makes perfect sense!*
DD-MM-YYYY	Most of Europe (in common, daily use; ISO 8601/EN 28601 European Standard when it really counts), Canada, Mexico. Still logic and can at least be understood why.
MM-DD-YYYY	USA. Doesn't make any sense what so ever. Completely illogical. (It's like saying an item costs one hundred five, two thousand dollars. $2 105.)

Eleven good reasons to use it - ISO-8601

Language independent - a true international standard from the International Organisation for Standardisation.
Cannot be confused with any other popular date notations.
Consistency with the common time notation system, where the larger unit (hour) is written in front of the smaller ones (minutes and seconds).
Easily readable and writeable by software (no month name to number conversion necessary).
Easily comparable and sortable with a trivial string comparison.
Strings containing a date followed by a time are also easily comparable and sortable e.g. 1996-01-15 22:45:37 with most significant value to the left.
The notation is short and has constant length, which makes both keyboard data entry and table layout easier.
Identical to the Chinese date notation, so the largest cultural group (>25%) on this planet is already familiar with it - so no feeble excuses like "but no-one uses this format...".
Date notations with the order "year, month, day" are in already widely used in Japan, Korea, Hungary, Sweden, Finland, Denmark to name just a few. Even people in the US are already used to at least the "month, day" ordering.
A 4-digit year representation would have avoided the Year 2000 problem. If only they had thought of that when computer technology was being developed...
Astronomers have been using this format for centuries.

From Campaign to get the Internet World to use the International Date Format ISO 8601.

Week Numbering

In addition, ISO 8601 formally defines the "calendar week" often encountered in commercial transactions in Europe.

The first calendar week of a year: week 1, is that week which contains the first Thursday of the year (or, equivalently, the week which includes January 4th of the year; the first day of that week is the previous Monday).

The last week: week 52 or 53 depending on the date of Monday in the first week, is that which contains December 31 of the year.

The first ISO calendar week of a given year starts with a Monday which can be as early as December 29th of the previous year or as late as January 4th of the present; the last calendar week can end as late as Sunday, January 3rd of the subsequent year.

ISO 8601 dates in year, week, and day form are written with a "W" preceding the week number, which bears a leading zero if less than 10, for example February 29th, 2000 is written as 2000-02-29 in year, month, day format and 2000-W09-2 in year, week, day form; since the day number can never exceed 7, only a single digit is required. The hyphens may be elided for brevity and the day number omitted if not required. You will frequently see date of manufacture codes such as "00W09" stamped on products; this is an abbreviation of 2000-W09, the ninth week of year 2000.

Weeks per Month

"The ISO standard does not define any association of weeks to months. A date is either expressed with a month and day-of-the-month, or with a week and day-of-the-week, never a mix." [http://en.wikipedia.org/wiki/ISO_week_date#Weeks_per_month]

SwedeTeam uses a scheme following ISO-8601's handling of first week of year:

First week of a month is week with at least 4 days in the month.

This means the previous month can end on a Sunday with day 27 in previous month.

Month	Wk	Date	Notes
April	17	2008-04-27 Sun	'Last week of April', per SwedeTeam's methodology
May	18	2008-04-28 Mon	'First week of May', per SwedeTeam's methodology
		2008-04-29 Tue
		2008-04-30 Wed
		2008-05-01 Thu	1 st day on new month on a Thursday
		2008-05-02 Fri	2
		2008-05-03 Sat	3
		2008-05-04 Sun	4
	19	2008-05-05 Mon
	19	...

Again, note that there are no (known to us) standards on this matter.

To set the record straight...:

Week Numbering

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