The Standardization of Message Sequence Charts

In this paper the most relevant issues of the standardization of the Message Sequence Chart (MSC) language within the CCITT Study Group X are discussed. The history of the new MSC recommendation Z.120 is sketched. Different types of diagrams which are closely related to MSCs are compared, since they build the basis for the MSC language. We distinguish these diagrams from the standardized MSC language by using the term Sequence Charts (SCs). Subsequently, the MSC language is introduced and several approaches towards a forthcoming formal MSC semantics are presented.