The following definitions are commonly used in this part of the Standard:
Unique identifier (UID): The scheme used to provide global unique identification for objects. It uses the structure defined by ISO 8824 for OSI Object Identifiers.
DICOM upper layer: The Upper Layer protocols are related to the Session, Presentation and part of the Application Layer of the ISO reference model. These protocols provide the Upper Layer Service. This Service is a proper subset of the ACSE Service and OSI Presentation Layer Service.