The establishment of an Association involves two DIMSE Service Users, one that is the Association-requestor and one that is the Association-acceptor. A DIMSE Service User may initiate an Association establishment by using the A-ASSOCIATE service described in PS3.8.

Included in the parameters of the A-ASSOCIATE service is the Application Context that specifies, among other things, the rules required for the coordination of initialization information corresponding to different DICOM Application Entities. The Application Contexts permitted for DIMSE are specified in Annex A.