An Application Context explicitly defines the set of application service elements, related options and any other information necessary for the inter working of Application Entities on an Association; in particular, it specifies the DIMSE Protocol used by the Application Layer.
Two Application Entities establish an Association by agreeing on an Application Context. The requester of an Association proposes an Application Context Name and the acceptor returns either the same or a different Application Context Name. The returned name specifies the Application Context to be used for this Association. The offer of an alternate Application Context by the acceptor provides a mechanism for limited negotiation. If the requester cannot operate in the acceptor's Application Context, it shall issue an A-Abort request primitive. Such a negotiation will facilitate the introduction of new versions of the DICOM Message Exchange Protocol in the future.