The fast-associate mechanism allows a session connection, including its embedded presentation connection and application association, to be established using a compressed form of the information that would otherwise be sent on the S-CONNECT exchange. The compressed form, called the upper-layer context identifier, is a reference to an upper-layer context specification, which is a definition of the fields of the application ACSE, presentation and session protocols that would be sent on the full-form connect messages. The upper-layer context identifier may be parameterized to include values for variable fields allowed by the full form protocols for the upper-layers.

Within the ACSE protocol, the addition is the definition of the construction of the User-summary parameter of the P‑CONNECT primitives from the semantics of the AARQ fields and the User-summary parameter of the corresponding A-ASSOCIATE primitive.