| Code | Display | Definition | V2 Concept Comment | V2 Concept Comment As Published | HL7 Concept Usage Notes |
| CAP | College of American Pathologist Accreditation Number | Allows for the ability to designate organization identifier as a "CAP" assigned number (for labs) | Use to identify assigning authority IDs, when an OID is not available. | | |
| CLIA | Clinical Laboratory Improvement Amendments | Clinical Laboratory Improvement Amendments. Allows for the ability to designate organization identifier as a "CLIA" assigned number (for labs) | Allows for the ability to designate organization identifier as a “CLIA” assigned number (for labs) | | |
| CLIP | Clinical laboratory Improvement Program | Clinical laboratory Improvement Program. Allows for the ability to designate organization identifier as a "CLIP" assigned number (for labs). Used by US Department of Defense. | Allows for the ability to designate organization identifier as a “CLIP” assigned number (for labs). Used by US Department of Defense. | | |
| DNS | Domain Name System | An Internet host name, in accordance with RFC 1035; or an IP address. Either in ASCII or as integers, with periods between components ("dotted" notation). | An Internet host name, in accordance with RFC 1035; or an IP address. Either in ASCII or as integers, with periods between components (“dotted” notation). | | |
| EUI64 | IEEE 64-bit Extended Unique Identifier | IEEE 64-bit Extended Unique Identifier is comprised of a 24-bit company identifier and a 40-bit instance identifier. The value shall be formatted as 16 ASCII HEX digits, for example, “AABBCC1122334455”. The 24-bit company identifier, formally known as Organizationally Unique Identifier (OUI-24), is guaranteed to be globally unique. The 40-bit extensions are assigned by manufacturers. This identifier is often used in equipment interfaces (e.g., “MAC” address format for IPv4 & IPv6). [See http://standards.ieee.org/regauth/oui/tutorials/EUI64.html for a detailed explanation of the format.] | IEEE 64-bit Extended Unique Identifier is comprised of a 24-bit company identifier and a 40-bit instance identifier. The value shall be formatted as 16 ASCII HEX digits, for example, “AABBCC1122334455”. The 24-bit company identifier, formally known as Organizationally Unique Identifier (OUI-24), is guaranteed to be globally unique. The 40-bit extensions are assigned by manufacturers. This identifier is often used in equipment interfaces (e.g., “MAC” address format for IPv4 & IPv6). [See http://standards.ieee.org/regauth/oui/tutorials/EUI64.htmlfor a detailed explanation of the format.]OUI-24 values are administered by the IEEE Registration Authority. | OUI-24 values are administered by the IEEE Registration Authority. | |
| GUID | globally unique identifier | Same as UUID. | Same as UUID. Retained for backward compatibility only as of v2.7; use UUID instead | Retained for backward compatibility only as of v2.7; use UUID instead | |
| HCD | CEN Healthcare Coding Identifier | The CEN Healthcare Coding Scheme Designator | The CEN Healthcare Coding Scheme Designator. Retained for backward compatibility only as of v2.7; does not identify Assigning Authorities | Retained for backward compatibility only as of v2.7; does not identify Assigning Authorities | |
| HL7 | HL7 registration schemes | HL7 registration schemes | Retained for backward compatibility only as of v2.7; HL7 assigns ISO OIDs for Assigning Authorities | Retained for backward compatibility only as of v2.7; HL7 assigns ISO OIDs for Assigning Authorities | |
| ISO | ISO Object Identifier | An International Standards Organization Object Identifier (OID), in accordance with ISO/IEC 8824. Formatted as decimal digits separated by periods; recommended limit of 64 characters | An International Standards Organization Object Identifier (OID), in accordance with ISO/IEC 8824. Formatted as decimal digits separated by periods; recommended limit of 64 characters | | |
| L | Local | These are reserved for locally defined coding schemes. | Locally defined coding entity identifier.Retained for backward compatibility only as of v 2.8 | | |
| L,M,N | Local | These are reserved for locally defined coding schemes. | Locally defined coding entity identifier.Retained for backward compatibility only as of v 2.8 | Retained for backward compatibility only as of v 2.8 | |
| M | Local | These are reserved for locally defined coding schemes. | Locally defined coding entity identifier.Retained for backward compatibility only as of v 2.8 | | |
| N | Local | These are reserved for locally defined coding schemes. | Locally defined coding entity identifier.Retained for backward compatibility only as of v 2.8 | | |
| NPI | US National Provider Identifier | Allows for the ability to designate organization identifier as a "NPI" assigned number (lab, any medical provider, can be a person or an organization) | Use to identify assigning authority IDs, when an OID is not available. Especially important in the CNN datatype. Namespace maintained and published in the US. | | |
| Random | Random | Usually a base64 encoded string of random bits.<p>Note: Random IDs are typically used for instance identifiers, rather than an identifier of an Assigning Authority that issues instance identifiers | Usually a base64 encoded string of random bits.Retained for backward compatibility only as of v2.7; equivalent to a locally defined entity identifier scheme; use L. M, or N instead. Note: Random IDs are typically used for instance identifiers, rather than an identifier of an Assigning Authority that issues instance identifiers | Retained for backward compatibility only as of v2.7; equivalent to a locally defined entity identifier scheme; use L. M, or N instead. | Retained for backward compatibility only as of v2.7; equivalent to a locally defined entity identifier scheme; use L. M, or N instead. |
| URI | Uniform Resource Identifier | Uniform Resource Identifier | | | |
| UUID | Universal Unique Identifier | The DCE Universal Unique Identifier, in accordance with RFC 4122. Recommended format is 32 hexadecimal digits separated by hyphens, in the digit grouping 8-4-4-4-12 | The DCE Universal Unique Identifier, in accordance with RFC 4122. Recommended format is 32 hexadecimal digits separated by hyphens, in the digit grouping 8-4-4-4-12 | | |
| x400 | X.400 MHS identifier | An X.400 MHS identifier. Recommended format is in accordance with RFC 1649 | Recommended format is in accordance with RFC 1649 | | |
| x500 | X500 directory Name | An X.500 directory name | | | |
