DICOM PS3.5 2019b - Data Structures and Encoding

9.2.2 Privately Defined Unique Identifiers

Privately Defined UIDs are commonly used within DICOM. However, such UIDs will not be registered by NEMA. Organizations that define private UIDs are responsible for properly registering their UIDs (at least obtain a registered <Org Root>) as defined for OSI Object Identifiers [ISO/IEC 9834-1]. The private organization defining the UID shall accept the responsibility of ensuring its uniqueness.

DICOM PS3.5 2019b - Data Structures and Encoding