1 Abstract

This document describes the processes whereby entries may be added to, changed, or removed from the XBRL International Units Registry. The Units Registry is an online listing of units that have been identified as potentially having wide utility. The Registry contains structured information about these units, including symbols and conversion factors. The Registry also lists associated datatypes, enabling processors to validate that the units used for an XBRL fact are appropriate for the reporting concept.

2 Goals

XBRL 2.1 provides a small set of standard units that may appear as QNames in the measure element of an XBRL instance document. These include "shares", "pure" and ISO 4217 currencies. As XBRL applications have emerged, unit declarations have appeared in XBRL instance documents having multiple names for equivalent meanings, and identical names having different meanings. The goal of the XBRL Units Registry (UTR) is to be a public, online data set that documents these units and their usage.

This document prescribes the process by which the UTR is maintained.

2.1 Relationship to other work

This document pertains to XBRL as defined in the XBRL 2.1 Specification and additional modules such as the Data Types Registry.

2.2 Terminology

abstract element, bind, concept, concrete element, context, Discoverable Taxonomy Set (DTS), duplicate items, duplicate tuples, element, entity, equal, essence concept, fact, instance, item, least common ancestor, linkbase, period, taxonomy, tuple, unit, taxonomy schema, child, parent, sibling, grandparent, uncle, ancestor, XBRL instance, c-equal, p-equal, s-equal, u-equal, v-equal, x-equal, minimally conforming XBRL processor, fully conforming XBRL processor and any other terms not specifically defined elsewhere in this document but which are used and defined in the XBRL 2.1 specification are as defined by XBRL 2.1.

BPB refers to the XBRL International Best Practices Board.

UTR refers to the Units Registry that is the subject of this specification.

UTR entry refers to the definition of an individual unit within the UTR.

UTRWG is the XBRL International Working Group assigned by the XSB to manage the UTR. At the time of writing, this is the XBRL International Base Specification and Maintenance Working Group, but this may be changed at any time by resolution of the XSB.

XSB refers to the XBRL Standards Board.

XII Participant refers to any individual elligible to participate in XBRL International Working Groups under XBRL International's membership policies.

2.2.1 Definitions

Green text denotes a definition of the term in bold font. For example:

An example term is defined by this text.

2.2.2 Non-normative notes

Text in a blue box denotes a non-normative explanatory note:

This is non-normative commentary.

2.2.3 Error codes

QNames in parenthetical red text after a "MUST" or "MUST NOT" statement prescribe standardised error codes to be used if the preceding condition is violated. For example,

The example property MUST be defined (eg:exampleErrorCode).

"MUST" or "MUST NOT" statements that do not have a prescribed error code are not automatically enforceable, and processors are not required to detect violations.

3 Maturity levels

The process by which the UTR is maintained is based loosely on XBRL International Technical Working Group Proccess, but significantly streamlined to reflect the relative simplicity of unit definitions.

UTR entries can have one of the following statuses:

• PROPOSED – an internal draft of a UTR entry.
• CR (Candidate Recommendation) — a public draft of a UTR entry.
• REC (Recommendation) – a finalised UTR entry.
• RR (Rescinded Recommendation) – a UTR entry that was previously published at REC status, but which is no longer recommended for use.

This document defines the processes required to progress UTR entries through these statuses.

4 Update Process

The process by which an entry is added to the UTR is described below. This is modelled on XBRL International Technical Working Group Proccess but is shortened to reflect the relative simplicity of a UTR entry compared to a specification.

A fast track process for ISO 4217 currency codes is documented in Section 4.9.

A summary of the process is shown in the diagram below.

4.1 Initial addition

Any XII participant may propose the addition of a UTR entry by submitting a draft of the entry to the UTRWG. The author of the submission is referred to as the sponsor.

The UTRWG will review the proposal, and MAY suggest changes before deciding to either accept or reject the submission. The decision will be made following the standard voting procedures for the group.

If the submission is accepted, it will be entered into the internal working copy of the UTR with a status of PROPOSED.

If the submission is rejected, the sponsor MAY appeal this decision to the XSB.

4.2 Publication as Candidate Recommendation

Once added at PROPOSED status, the UTRWG MAY request the XSB to approve publication of the UTR entry at CR status. This request MAY be made immediately, or the UTRWG MAY choose to batch multiple additions into a single update of the UTR. This decision should be taken in discussion with the sponsor, based on the urgency of the requirement for the UTR entry.

The XSB will review the proposed UTR entry and either approve publication at CR status, or request changes by the UTRWG.

If approved, the published UTR will be updated to include the new UTR entry.

4.3 Review period

UTR entries MUST remain published at CR status for a minimum of six weeks.

Once this period has elapsed, the sponsor MAY request progression of the UTR entry.

4.4 Progression from Candidate Recommendation

The UTRWG MUST consider any feedback received during the CR review period, and MAY make changes to the definition of the UTR entry as a result.

If there are substantive changes to the definition of the UTR entry, a further CR release is required, following the process in Section 4.2.

Otherwise, the UTRWG MAY request the XSB to approve the publication of the UTR entry at REC status.

The XSB will review the UTR entry and either approve publication at REC status, or request changes by the UTRWG.

If approved, the published UTR will be updated to include the UTR entry at REC status.

4.5 Updates to a REC UTR entry

Once published at REC status, a UTR entry MUST NOT be updated other than to apply errata corrections, or to rescind the entry (see Section 4.7).

An errata correction is an update that is restricted to addressing defects in the definition of a UTR entry.

An errata correction MAY be applied at any time based on an approved request from the UTRWG and approval by the XSB.

4.6 Withdrawing a UTR entry

Unless a unit has the status of REC it may be withdrawn from the UTR at any time upon request of the sponsor or the UTRWG, and with approval of the XSB.

A unit with the status REC MAY NOT be withdrawn in this manner but MUST follow the process in Section 4.7.

4.7 Rescinding a Recommended UTR entry

A UTR entry with REC status MAY be rescinded upon request of the UTRWG, and approval of the XSB.

If approved, the UTR entry is updated to RR status in the published UTR. This status indicates that the UTR entry is no longer recommended for use, but it is retained in the UTR in order to support existing XBRL reports that may use it.

4.8 Deleting a UTR entry

Rescinded UTR entries are not routinely removed from the UTR (see Section 4.7). Under exceptional circumstances, a UTR entry MAY be removed from the UTR. This requires approval of the XSB and MUST NOT be done any earlier than six months after moving to RR status.

4.9 ISO 4217 currency code process

The UTR contains UTR entries for ISO 4217 currency codes. These definitions are derived directly from the definitions published by ISO, and as such, an additional XBRL International review process is not required. This section provides a fast track process for the inclusion of new currency codes. Note that UTR entries for withdrawn ISO4217 codes are not routinely removed from the UTR.

The UTR tracks currencies included in the ISO 4217 list of Currency and Funds as described in this section. This follows the process defined for the XBRL Currency and Country code list taxonomies.

Where a currency code is added to the ISO 4217 list of Current Currency and Funds ("list one") that is not an excluded code, the UTR MAY be updated to include it as a new UTR entry at "REC" status without further review or approval.

A code is an excluded code if:

• it is a fund code;
• it is a precious metal code; or
• it has a ZZ prefix.

The fast track process described in this section is provided in addition to the standard processes for UTR maintenance; updates to ISO 4217 codes, including the addition of excluded codes, MAY be considered under the standard process.

5 UTR publication

The published UTR is a copy of the UTR that exists at the URL https://www.xbrl.org/utr/utr.xml.

Whenever the published UTR is updated, a copy of the UTR is also published at:

• https://www.xbrl.org/utr/YYYY-MM-DD/utr.xml

where YYYY-MM-DD is the date of the update.

Appendix A Intellectual property status (non-normative)

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to XBRL International or XBRL organizations, except as required to translate it into languages other than English. Members of XBRL International agree to grant certain licenses under the XBRL International Intellectual Property Policy (https://www.xbrl.org/legal).

This document and the information contained herein is provided on an "AS IS" basis and XBRL INTERNATIONAL DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

The attention of users of this document is directed to the possibility that compliance with or adoption of XBRL International specifications may require use of an invention covered by patent rights. XBRL International shall not be responsible for identifying patents for which a license may be required by any XBRL International specification, or for conducting legal inquiries into the legal validity or scope of those patents that are brought to its attention. XBRL International specifications are prospective and advisory only. Prospective users are responsible for protecting themselves against liability for infringement of patents. XBRL International takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Members of XBRL International agree to grant certain licenses under the XBRL International Intellectual Property Policy (https://www.xbrl.org/legal).

Appendix B Document history (non-normative)

Appendix C Errata corrections

This appendix contains a list of the errata that have been incorporated into this document. This represents all those errata corrections that have been approved by the XBRL International Unit Registry Task Force up to and including 2026-04-15.

No errata have been incorporated into this document.