Message Sequence Chart (MSC) - A Survey of the new CCITT Language for the Description to Traces within Communications Systems

Message Sequence Charts (MSCs) are a widespread means for description and graphical visualisation of selected system runs within distributed systems, especially telecommunication systems. Various kinds of MSCs with similar expressive power are used frequently within industry and standardisation bodies. Therefore, the CCITT (Comité Consultatif International Télégraphique et Téléphonique) attempts to harmonise their use by means of the new standard language Message Sequence Chart (MSC) in 1992 [Z120]. This paper presents a motivation for the MSC standardisation. The history of the standardisation process is briefly sketched. The MSC language is introduced. Some language constructs which may need further elaboration are pointed out and possible enhancements are proposed. Finally, an approach towards the definition of a clear MSC semantics is described.