HL7 OID Registry Frequently Asked Questions

I already have an OID, does HL7 have to assign a new one?

No. There are two separate operations, the creation of an OID under the HL7 root, and the registration of an OID. When you select “Internal” on the form data entry page, HL7 will create an OID under the HL7 root and register it. If you select “External” on that page, you must enter the literal numeric form (dots and numbers) of the OID you already have, which will then be registered.

I have no idea what Type I should select for my OID

HL7 has created a Type ontology for the OIDs in the HL7 registry to make it easier for the user community to search for OIDs they may be looking for; this type has nothing to do with ISO standards, or any intrinsic meaning or form of the OID itself. It is only a convenience for the users of this Registry.

The following Types have been defined for use in the HL7 OID Registry:

• Type 1

HL7 registered internal objects (other than published documents and organizational bodies)

Type 1 OIDs are only used for certain internal administrative functions at this time.

• Type 2

HL7 organizational bodies and groups

Type 2 OIDs are only used to identify an HL7 Group, such as a Working Group, or an International Council Member of HL7, such as HL7 Australia.

• Type 3

External group functioning as a Registration Authority

Type 3 OIDs are used for organizations that wish to create their own trees of OIDs for their use. If you will be assigning OIDs yourself under the OID that you are applying for, then you should select Type 3. This effectively delegates Registration Authority to your organization for all OIDs under this new Type 3 OID. No one else anywhere will create OIDs under your new root. Every OID created ‘under’ this new root will be considered by HL7 to be an ‘external’ OID, since you will have created it external to the HL7 OID Registry OID assignment software. These may be requested or registered by anyone.

• Type 4

Registered externally maintained identifier systems and namespaces

Type 4 OIDs are used for namespaces for identifiers that are public, and used widely, such as health card numbers, ID numbers assigned by jurisdictional authorities, etc. This is also used for any namespaces you may manage with your own defined OIDs under your own root, such as Medical Record Numbers or Accession Numbers, for example. This type of OID is typically used in the root of the version 3 datatype Instance Identifier.

• Type 5

HL7 Internal Code Systems

Type 5 OIDs are used only for HL7 created and maintained Coding Systems, that have been approved through the HL7 V3 Harmonization process. This type is assigned only by the group that applies decisions from the harmonization processes to the HL7 databases. These OIDs are typically used in the codSystem property of an HL7 Version 3 coded datatype.

• Type 6

Registered external coding systems

Type 6 is assigned to those OIDs that identify a Coding System or terminology that is created, published, and maintained by any organization outside of HL7. At this time, only an HL7 cochair or OID administrator can assign Type 6 to any OID. This type of OID is typically used in the codeSystem property of an HL7 Version 3 coded datatype.

• Type 7

HL7 published documents

Type 7 OIDs are used solely for HL7 published artifacts, and are assigned only by members of the HL7 publishing group. This includes standards, tutorial slides, implementation guides, databases, published RIM graphic billboards, etc.

• Type 8

HL7 OID registered documentation products and artifacts

Type 8 is currently not used.

• Type 9

HL7 Registered conformance profiles

Type 9 is used to indicate HL7 Conformance Profiles, published in the HL7 Profile Registry.

• Type 10

HL7 Registered Templates

Type 10 OIDs identify published Templates. These are created and registered by the Templates Workgroup, or by HL7 Workgroups that define and publish templates as part of their balloted standards.

• Type 11

HL7 defined and registered Value Sets

Type 11 OIDs identify Value Sets that have been created and published by HL7, and have been approved through the HL7 Harmonization processes only. These are used in HL7 Version 3 Model Binding and Context Binding mechanisms, and can only be assigned by members of the group that applies the HL7 Harmonization process approvals to the HL7 databases.

• Type 12

HL7 Version 2.x tables

Type 12 indicates that an OID identifies explicitly an HL7 Version 2.x Table, as published in the HL7 Version 2 series of standards. These exist to help facilitate development of translation capabilities between Version 2.x and Version 3/CDA interfaces.

• Type 13

Externally authored and curated Value Sets

Type 13 OIDs identify Value Sets that have been created, published, and are maintained by organizations outside of HL7. They may be registered by anyone, and are generally used in Hl7 Version 3 Model Binding and Context Binding mechanisms.

• Type 14

Assignment Ontology node

Type 14 OIDs may be used by any Registration Authority to indicate a structural ‘branch’ in the tree that they create under their own root, where the node is not any particular type of OID, the types will be below this node. Normally any node that is not a leaf is a registration authority, but some find that adding levels in the structure of the OIDs they create as Registration Authorities make the administration of the tree a bit easier. Each of the nodes in the HL7 tree that is the root of each of the Types is actually a Type 14 OID.

• Type 15

Small code sets externally defined

Type 15 OIDs are used to identify small code lists or sets that are defined and maintained by organizations outside of HL7. Where Value Sets are built upon underlying coding systems, short code lists are often ad-hoc values that are used in various applications, that are not components of a particular terminology or coding system. This type of OID may be used in the codeSystem property of a version 3 coded datatype.

• Type 17

Non-specified type

Type 17 OIDs are for any other type of object that does not fall into one of the other Type categories.

• Type 19

HL7 Examples

Type 19 OIDs are used for published examples; it is a truly meaningless identifier, as it is not to be used for any actual entities. This is the only kind of OID that may not be a unique identifier, i.e. it may refer to more than one object if it appears in different publications or slides. Type 19 OIDs are used ONLY in published examples in documents and slide presentations, and should NEVER appear in any implementation or any HL7 model instance.