A DICOM SOP class is a combination of a DICOM service command (DIMSE) and an information object.
DICOM services cover two worlds, the composite world (C) with its associated objects and services, such as images, and the normalized world (N) that contains services and objects used to manage those composite objects.
The composite commands operate on objects that are composed of several real world entities. It is not possible to delete a composite object using DICOM commands.
The Composite commands are :
A normalized object, however, consists of a single real world entity and is temporary, used for a single purpose, and then deleted. A normalized object study can be created, set, and even deleted using the normalized services. It also shows up as part of the composite study object to identify to which study the image belongs.
The Normalized commands provide two types of operations :
Notification service, that has the N_Event_Report command,
Operation services, that include