This Standard ECMA-87
a) defines the terminology, concepts, descriptive model and notation for generic aspects of the Virtual Terminal Service (VTS) in the Presentation Layer of the Reference Model of Open Systems Interconnection, (ISO 7498), including the criteria for classification of virtual terminal services,
b) defines in abstract form the interactions between two presentationservice-users (p-users) via the Virtual Terminal Service of Open Systems Interconnection,
c) gives in general terms an overview of the protocol between two presentation entities (p-entities) providing the presentation service (pservice), in particular VTS,
d) gives in general terms an overview of class-independent aspects of the usage of services of the Session Layer of OSI.
Appropriate relationships are established with the Generic Presentation Services GPS and Protocols GPP. This Standard ECMA-87 does not define any other interactions between a presentation service user and the presentation service. This Standard ECMA-87 is not an implementation specification for information processing systems.
This Standard ECMA-87 contains no explicit conformance statements but is referred to by individual VTS/P Class Standards and certain parts thereby acquire an implicit conformance requirement.