Guidance on Designing Label Generation Rulesets (LGRs) Supporting Variant Labels
RFC 8228

Approval announcement
Draft of message to be sent after approval:

From: The IESG <>
To: IETF-Announce <>
Cc: The IESG <>,, Scott Hollenbeck <>,,,
Subject: Document Action: 'Guidance on Designing Label Generation Rulesets (LGR) Supporting Variant Labels' to Informational RFC (draft-freytag-lager-variant-rules-06.txt)

The IESG has approved the following document:
- 'Guidance on Designing Label Generation Rulesets (LGR) Supporting
   Variant Labels'
  (draft-freytag-lager-variant-rules-06.txt) as Informational RFC

This document has been reviewed in the IETF but is not the product of an IETF
Working Group.

The IESG contact person is Alexey Melnikov.

A URL of this Internet Draft is:

Technical Summary

Rules for validating identifier labels and alternate representations of those labels (variants) are known as "Label Generation Rulesets" (LGRs); they are used for the implementation of identifier systems such as Internationalized Domain Names (IDNs).  This document describes ways of designing Label Generation Rulesets (LGRs) that support variant labels.  In designing LGRs, it is important to ensure that the label generation rules are consistent and well-behaved in the presence of variants.  The design decisions can then be expressed using the XML representation of LGRs that is defined in RFC7940.

Working Group Summary

This document was developed after the LAGER working group completed its work and was closed. Notice of the work was sent to the working group mailing list, but there was no interest in reviving the WG just to process this document. No controversial issues were identified on the working group mailing list, but no support was expressed, either. There were no last call review comments received from anyone on the working group mailing list.

Document Quality

The document largely reflects experience gathered from implementing RFC 7940 and creating rulesets based on it. No expert reviews are required, but the shepherd did solicit reviews from knowledgeable IETF participants inlcuding Paul Hoffman, John Klensin (see text below regarding John's review) and Andrew Sullivan. Marc Blanchet identified the following implementations: Viagenie developed a front-end interface under ICANN contract that is now open-sourced (see,; Asmus Freytag as part of ICANN Integration Panel work (not released as far as we know); Wil Tan as part of ICANN Integration Panel work (not released as far as we know).

John Klensin expressed concerns about publishing this document in IETF Stream.

A detailed review of the -03 version was completed on 24 January 2017 and results were sent to the IETF mailing list, the document author, and the area director. No significant technical issues were found at the time, but a need to add introductory context was identified. An early review of the -02 version identified a need to address minor ID nits and to add text to the security considerations section; those tasks were completed and incorporated in the -03 version. The -04 version was published to address comments received from John Klensin. The -05 version was published after a discussion of the -04 version, and with this version the Document Shepherd believed the document should be subjected to another IETF last call due to the breadth of changes made in the -04 version. The -06 version was published to address Andrew Sullivan's IETF LC comments, as well as feedback from IESG review (in particular Ben Campbell's comments).


 Scott Hollenbeck is the Document Shepherd.
 Alexey Melnikov is the Responsible Area Director.

RFC Editor Note

Please publish this document with "It has been approved for publication by the Internet Engineering Steering Group (IESG)." boilerplate text.