An abstract representation of the set of concepts, elements, functions, services, protocols, etc.as defined by the OSI Reference Model and the derived specific standards which, when applied, enable communications among open systems.

• 按照国际标准化组织(OSI)参考模型以及由其引出的能使开放系统进行通信的若干特定标准的定义、概念、元素、功能、服务、协议等集合的抽象表示。