パッケージ: libdate-iso8601-perl (0.005-1)

Perl handling of the three ISO 8601 numerical calendars

The international standard ISO 8601 "Data elements and interchange formats - Information interchange - Representation of dates and times" defines three distinct calendars by which days can be labelled. It also defines textual formats for the representation of dates in these calendars. Date::ISO8601 provides functions to convert dates between these three calendars and Chronological Julian Day Numbers, which is a suitable format to do arithmetic with. It also supplies functions that describe the shape of these calendars, to assist in calendrical calculations. It also supplies functions to represent dates textually in the ISO 8601 formats. ISO 8601 also covers time of day and time periods, but this module does nothing relating to those parts of the standard; this is only about labelling days.

The first ISO 8601 calendar divides time up into years, months, and days. It corresponds exactly to the Gregorian calendar, invented by Aloysius Lilius and promulgated by Pope Gregory XIII in the late sixteenth century, with AD (CE) year numbering. This calendar is applied to all time, not just to dates after its invention nor just to years 1 and later. Thus for ancient dates it is the proleptic Gregorian calendar with astronomical year numbering.