Idioms for -Charts

This paper presents an idiomatic construct for -charts which reflects the high-level specification construct of syn-chronization between activities. This, amongst others, has emerged as a common and useful idea during our use of -charts to design and specify commonly-occurring reac-tive systems. The purpose of this example, apart from any inherent interest in being able to use synchronization in a specification, is to show how the very simple language of -charts can used as a basis for a more expressive language built by definitional extension. 1