In order to serve as an SCP of the Query/Retrieve Service Class, a DICOM AE possesses information about the Attributes of a number of stored composite object SOP Instances. This information is organized into a well defined Query/Retrieve Information Model. The Query/Retrieve Information Model shall be a standard Query/Retrieve Information Model, as defined in this Annex of the DICOM Standard.
Queries and Retrievals are implemented against well defined Information Models. A specific SOP Class of the Query/Retrieve Service Class consists of an Information Model Definition and a DIMSE-C Service Group. In this Service Class, the Information Model plays a role similar to an Information Object Definition (IOD) of most other DICOM Service Classes.