CLDR Process


This document describes the Unicode CLDR Technical Committee, and its process for data collection, resolution, public feedback and release. The process is designed to be light-weight: in particular, the meetings are frequent, short, and informal. Most of the work is by email or phone, with a database recording requested changes in data.

When gathering data for a region and language, it is important to have multiple sources for that data to produce the most widely acceptable data. Initial versions of data were based on the best available sources, but CLDR data will be modified and improved, in successive versions, by more input from the contributors inside and outside of the Unicode Consortium.

It is important to note that CLDR is a Repository, not a Registration. That is, contributors should not expect that their contributions will simply be adopted into the repository; instead, it will be vetted against the best available information.

All inputs are open, and gathered via the CLDR Survey Tool or recorded in a bug/feature request database (CLDR Bug Reports). Changes in response to requests in the database may be entered into the repository snapshot over time by the maintainers of the repository, but the final approval of the release of any version of CLDR is up to the decision of the CLDR Technical Committee.

Formal Technical Committee Procedures

For more information on the formal procedures for the Unicode CLDR Technical Committee, see the Technical Committee Procedures for the Unicode Consortium.

Specification Changes

The UTS #35: Locale Data Markup Language (LDML) specification may be changed to add structure for new kinds of data or other features. Requests for changes are entered in the bug/feature request database (CLDR Bug Reports).

Structural changes are always backwards-compatible. That is, previous files will continue to work. Deprecated elements remain and can be used, although their usage is strongly discouraged.

There is a standing policy for structural changes that require non-trivial code for proper implementation, such as time zone fallback or alias mechanisms. These require the existence of at least a prototype implementation that demonstrates correct function according to the proposed specification.

Data Submission and Vetting Process

Once data for a country and language has been received, the data from the different sources will be compared to show agreements and differences. Initial data contributions are normally marked as draft; this may be changed once the data is vetted.

Note that there are two types of data in the repository:

  1. Common Data: The contents is decided upon by the CLDR Technical Committee, following its procedures and this process.
  2. Comparison data: The contributor can be an individual or an organization. Data is normally gathered by calling public APIs, to ensure that the data matches what is actually in use. The data is only for comparison, and will not be changed except where necessary to update the data to match the external source. The only requirement is that all changed data be versioned, and the Version Numbering Scheme be used.

Contributors are encouraged to use local language and country contacts, inside and outside their organization, to help vet current common data and any new proposals for addition or amendment of common data. In particular, national standards organizations are encouraged to be involved in the data vetting process.

For CLDR to add a new language just requires that the proposer to commit to providing at least the minimal localization (exemplar characters, months, days, date/time formats, translations for a few countries, languages, currencies, etc.). The exemplar characters, however, are required before the new locale can be added: see also Exemplar Character Sources. The new locale then becomes available for additional translations and vetting during the next review cycle.

Resolution Procedure

The following procedure is used when resolving differences in submitted data. At the end, for each field a single value will be chosen as optimal, while the others will have an alt=proposed attribute. The draft attribute on all the values will be set to one of 4 states:

  • unconfirmed
  • provisional
  • contributed (= minimally approved)
  • approved (equivalent to an absent draft attribute)

Implementations may choose the level at which they wish to accept data. They may choose to accept even unconfirmed data, especially if there is no translated alternative. Approved data is approved by the Technical Committee, as described by the resolution process below. This does not mean that the data is guaranteed to be error-free -- this is simply the best judgment of the committee according to the process.

User Levels

There are multiple levels of access and control:

Vetter Level Vote Description
Committee Vetters 8
  • Can vet and submit data for all locales
  • Can manage users in their organization
  • Can see the email addresses for all vetters
  • Technical Committee (TC) members
Expert Vetters 8
  • Can vet and submit data for a particular set of locales
  • Cannot manage other users.
  • Can see the email addresses for submitted data in their locales.
Regular Vetters 4
  • Can vet and submit data for a particular set of locales
  • Cannot manage other users.
  • Can see the email addresses for submitted data in their locales.
Guest Vetters 1
  • Can vet and submit data for a particular set of locales
  • Cannot manage other users.
  • Cannot see email addresses.
Locked Vetters 0
  • If a user is locked or removed, then his/er vote is zero.

These levels are decided by the technical committee and the TC representative for the respective organizations.

  • Unicode TC members (full/institutional/supporting) can assign its users to Regular or Guest level, and with approval of the TC, users at the Expert level.
  • Liaison or associate members can assign to Guest, or to other levels with approval of the TC.
    • The liaison/associate member him/herself gets TC status in order to manage users, but gets a Guest status in terms of voting, unless the committee approves a higher level.
  • Users assigned to "" are normally assigned as Guest, but the committee can assign a different level.

Voting Process

  • Each user gets one vote on each value, but the strength of the vote varies according to the user level according to the table above.
  • All values with survey tool errors get zero votes
    • For example, a date pattern of "14. september" instead of "dd MMM".
    • They cannot be voted for, and show a visible error.
    • Collision errors are an exception. They get normal votes, but are handled below.
  • For each value, each organization gets a vote based on the maximum (not cumulative) strength of the votes of its users who voted on that item.
    • That is, even if an organization has 10 Vetters voting for an value, if the highest level is regular vetter, then the vote count attributed to the organization as a whole is 4.
  • If there is a dispute (votes for different values) within an organization, then the majority vote for that organization is chosen. If there is a tie, then the vote most recently cast is the one that counts.
  • Batch data gets a status based on committee decision. Normally it should be based on the highest level of the people available to vote on it in the future.

All fields are then assessed as follows:

Optimal Field Value

For each release, there is one optimal field value determined by the following:

  • Add up the votes for each value from each organization.
  • Sort the  possible alternative values for a given field
    • by the most votes (descending)
    • then by UCA order of the values (ascending)
  • The first value is the optimal value (O).
  • The second value (if any) is the next best value (N).

Draft Status of Optimal Field Value

  1. Let O be the optimal value's vote, N be the vote of the next best value (or zero if there is none), and G be the number of organizations that voted for the optimal value. Let oldStatus be the draft status of the previously released value.
  2. Assign the draft status according to the first of the conditions below that applies:

    Resulting Draft Status Condition
    approved O > N and O ≥ 8, for established locales*
    O > N and O ≥ 4, for other locales
    contributed O > N and O ≥ 4 and oldstatus < contributed   
    O > N and O ≥ 2 and G ≥ 2 
    provisional O N and O  2 
    unconfirmed otherwise

  3. Established locales are currently found in coverageLevels.xml, with approvalRequirement[@votes="8"]
    • Some specific items have an even higher threshold. See approvalRequirement elements in coverageLevels.xml for details.
  4. If the oldStatus is better than the new draft status, then no change is made. Otherwise, the optimal value and its draft status are made part of the new release.
    • For example, if the new optimal value does not have the status of approved, and the previous release had an approved value (one that does not have an error and is not a fallback), then that previously-released value stays approved and replaces the optimal value in the following steps.
It is difficult to develop a formulation that provides for stability, yet allows people to make needed changes. The CLDR committee welcomes suggestions for tuning this mechanism. Such suggestions can be made by filing a new ticket.

Further Processing

After the optimal value is chosen:

  • Collisions errors are resolved by retaining one of the values and removing the other(s).
    • The choice is based on the judgment of the committee, typically according to which field is most commonly used. When an item is removed, an alternate may then become the new optimal value.
  • All other values with errors are removed.
  • Non-optimal values are handled as follows:
    • Those with no votes are removed.
    • Those with votes are marked with alt=proposed and given the draft status: unconfirmed

If a locale does not have minimal data (at least at a provisional level), then it may be excluded from the release. Where this is done, it may be restored to the repository for the next submission cycle.

Note: Starting with CLDR 1.7, we are planning to save votes across releases, for any active (unlocked) voters. However, where there are English changes, old votes will be discarded.

This process can be fine-tuned by the Technical Committee as needed, to resolve any problems that turn up. A committee decision can also override any of the above process for any specific values.

For more information see the key links in CLDR Survey Tool (especially the Vetting Phase).


  • If data has a formal problem, it can be fixed directly (in CVS) without going through the above process. Examples include:
    • syntactic problems in pattern, extra trailing spaces, inconsistent decimals, mechanical sweeps to change attributes, translatable characters not quoted in patterns, changing ' (punctuation mark) to curly apostrophe or s-cedilla to s-comma-below, removing disallowed exemplar characters (non-letter, number, mark, uppercase when there is a lowercase).
    • These are changed in-place, without changing the draft status.
  • Linguistically-sensitive data should always go through the survey tool. Examples include:
    • names of months, territories, number formats, changing ASCII apostrophe to U+02BC modifier letter apostrophe or U+02BB modifier letter turned comma, or U+02BD modifier letter reversed comma, adding/removing normal exemplar characters.
  • The TC committee can authorize bulk submissions of new data directly (CVS), with all new data marked draft="unconfirmed" (or other status decided by the committee), but only where the data passes the CheckCLDR console tests.
  • The survey tool does not currently handle all CLDR data. For data it doesn't cover, the regular bug system is used to submit new data or ask for revisions of this data. In particular:


There may be conflicting common practices or standards for a given country and language. Thus LDML provides keyword variants to reflect the different practices. For example, for German it allows the distinction between PHONEBOOK and DICTIONARY collation.

When there is an existing national standard for a country that is widely accepted in practice, the goal is to follow that standard as much as possible. Where the common practice in the country deviates from the national standard, or if there are multiple conflicting common practices, or options in conforming to the national standard, or conflicting national standards, multiple variants may be entered into the CLDR, distinguished by keyword variants or variant locale identifiers.

Where a data value is identified as following a particular national standard (or other reference), the goal is to keep that data aligned with that standard. There is, however, no guarantee that data will be tagged with any or all of the national standards that it follows.

Maintenance Releases

Maintenance releases, such as 26.1, are issued whenever the standard identifiers change (that is, BCP 47 identifiers, Time zone identifiers, or ISO 4217 Currency identifiers).  Updates to identifiers will also mean updating the English names for those identifiers.

Corrigenda may also be included in maintenance releases. Maintenance releases may also be issued if there are substantive changes to supplemental (non-language) data. An example of supplemental data additions would be adding more transforms, or adding more script-language info.

Normally there are no maintenance releases for language data, but the committee may decide to issue one if the situation warrants. Normally there are no major changes in the specification.

The structure and DTD may change, but except for additions or for small bug fixes, data will not be changed in a way that would affect the content of resolved data.

Data Retention Policy

Public Feedback Process

The public can supply formal feedback into CLDR via the Survey Tool or by filing a Bug Report or Feature Request. There is also a public forum for questions at CLDR Mailing List (details on archives are found there).

Anyone can also asked to be added to a list that will receive notification of new CLDR bugs, so they can track issues if they want. Anyone can also to reply to any bug report to add comments or questions.

  • To subscribe, send a note to "" (use an at sign instead of the +) and put "subscribe cldr-bugrfe" in the subject line.
  • To unsubscribe, put "unsubscribe cldr-bugrfe" in the subject line instead.

There is also a members-only CLDR mailing list for members of the CLDR Technical Committee.

Public Review Issues may be posted in cases where broader public feedback is desired on a particular issue.

Be aware that changes and updates to CLDR will only be taken in response to information entered in the Survey Tool or by filing a Bug Report or Feature Request. Discussion on public mailing lists is not monitored; no actions will be taken in response to such discussion -- only in response to filed bugs. The process of checking and entering data takes time and effort; so even when bugs/feature requests are accepted, it may take some time before they are in a release of CLDR.

Data Release Process

Version Numbering

The locale data is frozen per version. Once a version is released, it is never modified. Any changes, however minor, will mean a newer version of the locale data being released. The version numbering scheme is "xy.z", where z is incremented for maintenance releases, and xy is incremented for regular semi-annual releases as defined by the regular semi-annual schedule

Release Schedule

Early releases of a version of the common locale data will be issued as either alpha or beta releases, available for public feedback. The dates for the next scheduled release will be on CLDR Project.

The schedule milestones are listed below.

MilestoneTrac PhaseDescription
Survey Tool Beta Start  After this point, users can try out the survey tool and supply feedback
Data Submission Start dsubAfter this point, users can add data and vet (vote for) for data
Data Vetting Start dvetAfter this point, users can vet (vote for) data, and can add in certain disputed cases
Data Resolution Start  After this point, the data and structure are resolved, verified, and correctedby the committee.
Final Candidate Available rcThe final Candidate available for testing. Only showstoppers fixed after this point.
Release Available finalThe stable, referenceable version is released.

Labels in the Trac column are the trac phase, used to mark tickets that need to be complete before the phase starts. Each phase ends at 24:00 (midnight, US Pacific Time) on the day in question.

Meetings and Communication

The currently-scheduled meetings are listed on the Unicode Calendar. Meetings are held by phone, every week at 8:00 AM Pacific Time (-08:00 GMT in winter, -07:00 GMT in summer). Some meetings may be skipped if they conflict with holidays or other Unicode meetings.

There is an internal email list for the Unicode CLDR Technical Committee, open to Unicode members and invited experts. All national standards bodies who are interested in locale data are also invited to become involved by establishing a Liaison membership in the Unicode Consortium, to gain access to this list.

Notification of the telephone numbers and passcode, and agenda, and any change in schedule are sent out on this email list.


The current Technical Committee Officers are:

  • Chair: Mark Davis (Google)
  • Vice-Chair: John Emmons (IBM)