The core implementations for the and DateTime::Duration
modules originally came from Date::ICal and Date::ICal::Duration, both
of which were written by Rich Bowen <> with help
from the Reefknot team. Nowadays much of this code has been rewritten
to the point that it is fundamentally original work.

Parts of the API come from Time::Piece, by Matt Sergeant
<>, who had help from Jarkko Hietaniemi <>.
That API was originally created by Larry Wall. None of the code is

The DateTime::Locale functionality is based in part on the
Date::Language modules that come with Graham Barr's <>
TimeDate module suite.  The strftime method in this module also
borrows heavily from Graham's implementation.

The week number and week year algorithms were taken from Steffen
Beyer's Date::Calc module, but rewritten in Perl from scratch.

The code for handling nanoseconds and the code for leap seconds were
both largely written by Flavio Soibelmann Glock, who also has
contributed various other features and fixes.

Many others have helped out with code, ideas, and bug reports.  See
the Changes file for details.