This Recommendation International Standard defines the security audit trail function. The security audit trail function is a systems management function which may be used by an application process in a centralized or decentralized management environment to exchange information and commands for the purpose of systems management, as defined by CCITT Rec. X.700 ISO 7498-4. This Recommendation International Standard is positioned in the application layer of CCITT Rec. X.200 ISO 7498 and is defined according to the model provided by ISO/IEC 9545. The role of systems management functions is described by CClTT Rec. X.701 ISO/IEC 10040.This Recommendation International Standard- establishes user requirements for the service definition needed to support the security audit trail reporting function;- defines the service provided by the security audit trail reporting function;- specifies the protocol that is necessary in order to provide the service;- defines the relationship between the service and management notifications;- defines relationships with other systems management functions;- specifies conformance requirements.This Recommendation International Standard does not define- a security audit, nor how to perform one. A security audit may be used to assist in assessing the effectiveness of a security policy. The security policy identifies the categories of security-related events that require auditing, and the location of the security audit trail log in which they are to be recorded;- the nature of any implementation intended to provide the security audit trail function;- the occasions where the use of the security audit trail function is appropriate;- the services necessary for the establishment, normal and abnormal release of a management association;- any other notifications defined by other Recommendations International Standards which may be of interest to a security administrator.