Health Level 7 (HL7), Inc., an ANSI-accredited standards developing organization operating in the healthcare arena
HL7 Version 3 artefacts use OIDs to identify coding schemes and identifier namespaces.
The HL7 OID registry is structured as follows: 1: HL7 registered internal objects (other than published documents and organizational bodies); 2: HL7 organizational bodies and groups; 3: External groups that have been issued an HL7 OID root for their own use; 4: Registered externally maintained identifier systems and namespaces; 5: HL7 Internal Code Systems; 6: Registered external coding systems (with an HL7 issued OID); 7: HL7 published documents (standards, tutorial slides, implementation guides, databases, published Reference Information Model (RIM) graphic billboards, etc); 8: HL7 OID registered documentation products and artifacts; 9: HL7 Registered conformance profiles; 10: HL7 Registered Templates; 11: HL7 defined and registered Value Sets; 12: HL7 Version 2.x tables as code systems; 13: Externally authored and curated Value Sets, HL7 registered; 14: Internal use; 15: Small code sets externally defined (similar to v2.x tables); 19: HL7 Examples Root used for published examples; meaningless identifier, not to be used for any actual entities.
The process of registering an OID with HL7 is the addition to a central registry of an OID and its descriptive data. The OID doesn't have to be within the HL7 root OID or any specific other root or branch OID. Once a scheme has been registered, no other OIDs that identify the same scheme can be registered.