Fragment Identifier Prefix Registration for XLIFF 2

If you are using your own extension elements or attributes in XLIFF 2, and the extension has identifiers, you must register the prefix corresponding to your extension's namespace so tools can point to the element following the Fragment Identifier mechanism of XLIFF 2.

To register a prefix

Send a request for prefix registration to the public xliff-comment mailing list:

  1. Subscribe to the xliff-comment list by sending a blank email message to:

  2. Confirm your subscription request by replying to the confirmation email message you will receive from OASIS.
  3. Watch your inbox for a Welcome message indicating that your subscription is now active.
  4. Now you can send your request for prefix registration to

The email subject must clearly indicate this is about registering a fragment identifier prefix.

The email MUST contain:

Optionally you can also include:

* Any other information you deem necessary

Once received, your request will be promptly checked for correctness and verified against existing prefixes. If there is a problem, you will be notified as soon as possible.

If your prefix is valid and available, one of the TC members responsible for the registration will add it to the registry and post an email to the xliff-comment list announcing the new prefix.

Note that the TC reserves the right to refuse prefixes if they are deemed to cause potential conflicts or problems.


What if I don't register a prefix with my extension?

If your extension doesn't use IDs it's OK.

If your extension uses IDs, no-one will be able to point to an element of your extension if they don't know the prefix to use, and more importantly: XLIFF 2 validators will flag as invalid any documents using fragment identifiers with un-registered prefixes.

Are there other requirements for the ID mechanism?

Yes, your IDs values must follow the rules defined here:

The general Fragment identifier mechanism is described here:

What is the length limit for the prefix?

It must be at least two characters long. There is no maximum limit but you should try to keep its short: the prefix will be used in URL fragment identifiers where shorter is better.

Are those prefixes the same as the ones used in custom values like in subState or subType?

Technically no. However, it is strongly encouraged to A) be consistent and use the same prefix for both mechanisms in your custom data and B) to register the prefixes even if they are only for attribute values. In such case it is recommended for the registered URI to be a URL pointing to a public page where the attribute values are described.

How long does it take to register a prefix?

Not long, the TC members assigned to the task should be able to process your request quickly, likely within 24h if the request has no issue.

What if I submit the same prefix as someone else at the same time?

The first request posted (according the date in the xliff-comment archives) would get the prefix, the second one would have to pick another prefix.

Can my prefix includes non-ASCII characters?

Yes, as long as the string is a valid NMTOKEN it should be fine.

Can I change the namespace URI for a given prefix after I've registered it?

Most likely not. But the TC may make exceptions.

Can I change the prefix for a namespace URI after I've registered it?

Most likely not. But the TC may make exceptions.

File Format

The format of the registry file is the follows:


Note that a unique prefix may be associated with several URIs (e.g. several versions of the same namespace)

FragIDPrefixRegistration (last edited 2018-01-23 17:45:09 by ysavourel)