DateTime is a class for the representation of date/time combinations, and
is part of the Perl DateTime project. For details on this project please
see the http://datetime.perl.org/ manpage. The DateTime site has a FAQ
which may help answer many "how do I do X?" questions. The FAQ is at the
http://datetime.perl.org/wiki/datetime/page/FAQ manpage.

It represents the Gregorian calendar, extended backwards in time before its
creation (in 1582). This is sometimes known as the "proleptic Gregorian
calendar". In this calendar, the first day of the calendar (the epoch), is
the first day of year 1, which corresponds to the date which was
(incorrectly) believed to be the birth of Jesus Christ.

The calendar represented does have a year 0, and in that way differs from
how dates are often written using "BCE/CE" or "BC/AD".

For infinite datetimes, please see the DateTime::Infinite module.