Description:

Calendar provides an API for building calendar data structures. Using
the simple iterator and it's "query" API, a user interface can easily be
built on top of the calendar data structure, at the same time easily
connecting it to some kind of underlying data store, where "event"
information is being held.

It provides different calculation "engines" the default being based on
Unix timestamps (offering fastest performance) with an alternative using
PEAR::Date which extends the calendar past the limitations of Unix
timestamps. Other engines should be implementable for other types of
calendar (e.g. a Chinese Calendar based on lunar cycles).