This set of documents, collectively called the iCalendar Transport-independent Interoperability Protocol, or iTIP, defines a transport-independent message protocol to allow for searching for busy time and the scheduling of events, journal entries, or journal entries on different calendaring and scheduling systems. These documents are based on earlier work documented in the iCalendar format. Because iCalendar delt mainly with the format of calendaring information and said so little about the method for conveying scheduling semantics, these documents add scheduling semantics to the base calendaring functionality defined in iCalendar.