以抽象的方式定义OSI表示层提供的外部可见服务，包括用户/服务边界处的基本动作和事件、与每个基本动作和事件相关的参数数据、这些动作和事件之间的关系以及这些动作和事件的有效序列。定义的服务是由OSI面向连接的表示协议提供的面向连接的服务和由OSI无连接表示协议提供的无连接的服务，每个服务都与OSI会话服务一起提供。

Defines in an abstract way the externally visible service provided by the OSI presentation layer in terms of the primitive actions and events at the user/service boundary, the parameter data associated with each primitive action and event, the relationship between, and the valid sequences of, those actions and events. The service defined is the connection-oriented service which is provided by the OSI connection-oriented presentation protocol and the connectionless service which is provided by the OSI connectionless presentation protocol, each in conjunction with the OSI session service.