I have found two resources about date and time and their formats. One is the <a href="http://www.iso.ch/iso/en/prods-services/popstds/datesandtime.html";>ISO Standard 8601</a>, the second is a german <a href="http://www.pjh2.de/datetime/weeknumber/index.php";>page</a>. On this page along with other information all definitions used by Windows is listed.
According to this page the ISO Standard has been established in Europe and most industrial countries. In USA it is ANSI X3.30-1985(R1991) and NIST FIPS 4-1. Since the ANSI definition you mentioned allows only Sunday (Jewish) or Monday (Christian) as first day of the week it ignores the Islamic world. For them the first day is Saturday. I could not gather information about Buddhistic or Hinduism based countries. For my application and the market aimed the ISO format is the one which will be choosen. Using %W and handling of week 0 should do it. Waldemar
