1.1 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 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; 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; 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 following: general models of security exchange protocol functions and security transformations, based on the concepts described in the OSI Upper Layers Security Model (ITU-T Rec. X.803 | ISO/IEC10745); 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; a set of informative guidelines as to the application of the generic upper layers security facilities covered by this series of Recommendations | International Standards. 1.3 This Recommendation | International Standard does not define the following: a complete set of upper layer security facilities which may be required by other Recommendations | International Standards; a complete set of security facilities for specific applications; the mechanisms employed to support security services. 1.4 The security exchange model, and supporting notation, are intended both for use as the basis of defining the security exchange service element in subsequent parts of this series of Recommendations | International Standards, and for use by any other ASE which may import security exchanges into its own specification.