As the service provided by the Presentation consists in enabling some exchange of Application Data Values regardless of their representations (to ensure the openness of the communication), the representations attached to the Application Data Values is of no interest for the Applications themselves.

The applications must agree on the nature of the values they will exchange, in order to make sure that they have some common understanding of the nature of their PDUs (Protocol Data Units).

The components which are actually concerned by these representations are the Presentation protocol machines. They must agree on the way the values of the applications will be represented in the exchange.