This series of Recommendations | International Standards defines a set of generic facilities to assist in the provision of security services in OSI applications. 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 of OSI; 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 protecting transfer syntax, associated with Presentation Layer support for security services in the Application Layer.