The DICOM Information Model is derived from the DICOM Model of the Real-World. The DICOM Information Model presented by Figures 7-2a, 7-2b , 7-2c and 7-2d identify the various IODs specified by this Standard and their relationships. There is not always a one-to-one correspondence between DICOM Information Object Definitions and Real-World Objects. For example a Composite IOD contains Attributes of multiple real-world objects such as series, equipment, frame of reference, study and patient.
The entities in Figures 7-2a, 7-2b, 7-2c and 7-2d correspond to IODs defined in Annexes A through C.