1范围和应用领域ISO 7498的这一部分:（a）提供了安全服务和相关机制的一般描述，可通过参考模型提供；以及（b）定义参考模型中可提供服务和机制的位置。ISO 7498的本部分扩展了ISO 7498的应用范围，涵盖开放系统之间的安全通信。已为基本参考模型的所有层确定了基本安全服务和机制及其适当位置。此外，还确定了安全服务和机制与基本参考模型的体系结构关系。终端系统、装置和组织可能需要额外的安全措施。这些措施适用于各种应用环境。支持此类额外安全措施所需的安全服务的定义不在本标准的范围内。 OSI安全功能只涉及通信路径的那些可见方面，这些方面允许终端系统在它们之间实现信息的安全传输。OSI安全与终端系统、装置和组织所需的安全措施无关，除非这些措施对OSI中可见的安全服务的选择和位置有影响。安全的后几个方面可以标准化，但不在OSI标准的范围内。ISO 7498的本部分增加了ISO 7498中定义的概念和原则；它不会修改它们。它不是一个实现规范，也不是评估实际实现的性能的基础。

1Scope and Field of ApplicationThis part of ISO 7498:(a) provides a general description of security services and related mechanisms, which may be provided by the Reference Model; and(b) defines the positions within the Reference Model where the services and mechanisms may be provided.This part of ISO 7498 extends the field of application of ISO 7498, to cover secure communications between open systems.Basic security services and mechanisms and their appropriate placement have been identified for all layers of the Basic Reference Model. In addition, the architectural relationships of the security services and mechanisms to the Basic Reference Model have been identified. Additional security measures may be needed in end-systems, installations and organizations. These measures apply in various application contexts. The definition of security services needed to support such additional security measures is outside the scope of this standard.OSI security functions are concerned only with those visible aspects of a communications path which permit end systems to achieve the secure transfer of information between them. OSI Security is not concerned with security measures needed in end systems, installations, and organizations, except where these have implications on the choice and position of security services visible in OSI. These latter aspects of security may be standardized but not within the scope of OSI standards.This part of ISO 7498 adds to the concepts and principles defined in ISO 7498; it does not modify them. It is not an implementation specification, nor is it a basis for appraising the conf ormance of actual implementations.