MCAL stands for Modular Calendar Access Library.
Libmcal is a C library for accessing calendars. It's written to be very modular, with pluggable drivers. MCAL is the calendar equivalent of the IMAP module for mailboxes.
With mcal support, a calendar stream can be opened much like the mailbox stream with the IMAP support. Calendars can be local file stores, remote ICAP servers, or other formats that are supported by the mcal library.
Calendar events can be pulled up, queried, and stored. There is also support for calendar triggers (alarms) and recurring events.
With libmcal, central calendar servers can be accessed, removing the need for any specific database or local file programming.
To get these functions to work, you have to compile PHP with --with-mcal. That requires the mcal library to be installed. Grab the latest version from http://mcal.chek.com/ and compile and install it.
The following constants are defined when using the MCAL module. For weekdays :