DICOM PS3.3 2021e - Information Object Definitions
A.7.4.2.2 Active Image Area Overlays

The Overlay Plane Module and Multi-Frame Overlay Module may be used to describe the active image area by use of a either a single frame overlay that applies to all image frames, or per-frame overlays. In either case, an Overlay Type (60xx,0040) value of R and an appropriate Overlay Subtype (60xx,0045) value is used. In the case of a single frame overlay that applies to all image frames, the active area specified by such an active image area overlay will be at the same location in every frame of the image as specified in Section C.9.2 Overlay Plane Module.

DICOM PS3.3 2021e - Information Object Definitions