In the request/indication, this is a list of Attributes to be matched against the values of the Attributes of known composite SOP Instances of the performing DIMSE-service-user. The list of Attributes allowed and the rules for the construction are specified in PS 3.4.
Note: The Identifier is specified as U in the Response/Confirmation, but Services defined in PS 3.4 that use this primitive may impose mandatory or conditional requirements on its presence.
In the response/confirmation, this is a list of Attributes which provide status information about the C-GET operation. The list of Attributes allowed and the rules which define the usage of the Identifier are specified in PS 3.4.