Time unit constructors for the ISO 8601 calendar system. These units can be
used with linear_time() to create custom time representations.
Details
The following ISO 8601 time units are available:
tu_isoyear(): ISO year unit (years start on the week containing the first Thursday)tu_week(): Week unit (7-day periods)
ISO 8601 weeks always start on Monday and the first week of a year is the week containing the first Thursday of that year. This means that some days in early January may belong to the last week of the previous ISO year, and some days in late December may belong to the first week of the next ISO year.
See also
linear_time() for creating custom time representations,
yearweek() for a pre-defined ISO 8601 year-week representation