Abstract: A calendar system incorporates information from publication sources for display as information events on a calendar of the calendar system. A respective user of the calendar system may subscribe to an identified publication source that is internal or external to the calendar system. The calendar system determines whether data from the identified publication source conforms with a predefined calendar data exchange format. If data from the identified publication source conforms with the predefined calendar data exchange format, the calendar system may import data from the publication source and transmit the data (including data for at least one information event) to at least one client for rendering of the calendar system. If data from the identified publication source fails to conform with the predefined calendar data exchange format, the calendar system may re-format the data to conform to a calendar data exchange format that is compatible with the calendar system.