| Code | Description | Comment | Version |
| CAP | College of American Pathologist Accreditation Number | | added v2.9 |
| CLIA | Clinical Laboratory Improvement Amendments | | added v2.7 |
| CLIP | Clinical laboratory Improvement Program | | added v2.7 |
| DNS | Domain Name System | | added v2.3 |
| EUI64 | IEEE 64-bit Extended Unique Identifier | OUI-24 values are administered by the IEEE Registration Authority. | added v2.7 |
| GUID | globally unique identifier | Retained for backward compatibility only as of v2.7; use UUID instead | added v2.3 |
| HCD | CEN Healthcare Coding Identifier | Retained for backward compatibility only as of v2.7; does not identify Assigning Authorities | added v2.3 |
| HL7 | HL7 registration schemes | Retained for backward compatibility only as of v2.7; HL7 assigns ISO OIDs for Assigning Authorities | added v2.3 |
| ISO | ISO Object Identifier | | added v2.3 |
| L | Local | Retained for backward compatibility only as of v 2.8 | added v2.3 |
| L,M,N | Local | Retained for backward compatibility only as of v 2.8 | added v2.3 |
| M | Local | Retained for backward compatibility only as of v 2.8 | added v2.3 |
| N | Local | Retained for backward compatibility only as of v 2.8 | added v2.3 |
| NPI | US National Provider Identifier | | added v2.9 |
| Random | Random | Retained for backward compatibility only as of v2.7; equivalent to a locally defined entity identifier scheme; use L. M, or N instead. | added v2.3 |
| URI | Uniform Resource Identifier | | added v2.5 |
| UUID | Universal Unique Identifier | | added v2.3 |
| x400 | X.400 MHS identifier | | added v2.3 |
| x500 | X500 directory Name | | added v2.3 |