Describes the main ideas of an extension of Message Sequence Charts(MSC) to improve the ability of MSC to specify some a pplications (especially in the telecommunication field) more clearly and accurat ely.

• 为了使消息顺序图(messagesequencecharts；MSC)能更好地满足在通信领域应用的需要；在现有MSC标准的基础上；参考了其他常用的顺序图；并采用面向对象的思想；对MSC的消息机制进行扩展.