The International Standard ISO 8601 has decreed that Monday shall be the first day of the week. A week that lies partly in one year and partly in another is assigned a number in the year in which most of its days lie. That means that week number 1 of any year is the week that contains 4th January.
在国际标准 ISO 8601 中已指出每周的第一天为“星期一”。对于跨越两个年度的星期，会以该星期的大多数天数所在的年度为基准指定编号。这意味着，在任何年度中编号为 1 的星期均包含一月四日。