The Query/Retrieve Service Class defines an application-level class-of-service which facilitates the simple management of composite object instances in a manner functionally similar to ACR-NEMA 300-1988. The types of queries which are allowed are not complex. This Service Class is not intended to provide a comprehensive generalized database query mechanism such as SQL. Instead, the Query/Retrieve Service Class is focused towards basic composite object instance information queries using a small set of common Key Attributes.
In addition, the Query/Retrieve Service Class provides the ability to retrieve/transfer a well-identified set of composite object instances. The retrieve/transfer capability allows a DICOM AE to retrieve composite object instances from a remote DICOM AE or request the remote DICOM AE to initiate a transfer of composite object instances to another DICOM AE.
Note: Functional similarity to ACR-NEMA 300-1988 facilitates the migration to DICOM.