This series of Recommendations | International Standards defines a set of generic facilities to assist in the provision of security services in application layer protocols. These include: a) a set of notational tools to support the specification of selective field protection requirements in an abstract syntax specification, and to support the specification of security exchanges and security transformations; b) a service definition, protocol specification and PICS proforma for an application-service-element (ASE) to support the provision of security services within the Application Layer; c) a specification and PICS proforma for a security transfer syntax, associated with Presentation Layer support for security services in the Application Layer. 1.2 This Recommendation | International Standard defines the service provided by the Security Exchange Service Element (SESE). The SESE is an ASE which allows the communication of security information to support the provision of security services within the Application Layer