Guidance on Designing Label Generation Rulesets (LGRs) Supporting Variant Labels
RFC 8228
Document | Type |
RFC - Informational
(August 2017; Errata)
Was draft-freytag-lager-variant-rules (individual in art area)
|
|
---|---|---|---|
Author | Asmus Freytag | ||
Last updated | 2020-01-21 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized with errata bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | Scott Hollenbeck | ||
Shepherd write-up | Show (last changed 2017-04-17) | ||
IESG | IESG state | RFC 8228 (Informational) | |
Consensus Boilerplate | No | ||
Telechat date | |||
Responsible AD | Alexey Melnikov | ||
Send notices to | "Scott Hollenbeck" <shollenbeck@verisign.com> | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | No IANA Actions |
Internet Engineering Task Force (IETF) A. Freytag Request for Comments: 8228 August 2017 Category: Informational ISSN: 2070-1721 Guidance on Designing Label Generation Rulesets (LGRs) Supporting Variant Labels Abstract 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 to design LGRs to 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 RFC 7940. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force (IETF). It has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc8228. Freytag Informational [Page 1] RFC 8228 Variant Rules August 2017 Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Variant Relations . . . . . . . . . . . . . . . . . . . . . . 4 3. Symmetry and Transitivity . . . . . . . . . . . . . . . . . . 5 4. A Word on Notation . . . . . . . . . . . . . . . . . . . . . 5 5. Variant Mappings . . . . . . . . . . . . . . . . . . . . . . 6 6. Variant Labels . . . . . . . . . . . . . . . . . . . . . . . 7 7. Variant Types and Label Dispositions . . . . . . . . . . . . 7 8. Allocatable Variants . . . . . . . . . . . . . . . . . . . . 8 9. Blocked Variants . . . . . . . . . . . . . . . . . . . . . . 9 10. Pure Variant Labels . . . . . . . . . . . . . . . . . . . . . 10 11. Reflexive Variants . . . . . . . . . . . . . . . . . . . . . 11 12. Limiting Allocatable Variants by Subtyping . . . . . . . . . 12 13. Allowing Mixed Originals . . . . . . . . . . . . . . . . . . 14 14. Handling Out-of-Repertoire Variants . . . . . . . . . . . . . 15 15. Conditional Variants . . . . . . . . . . . . . . . . . . . . 16 16. Making Conditional Variants Well Behaved . . . . . . . . . . 18 17. Variants for Sequences . . . . . . . . . . . . . . . . . . . 19 18. Corresponding XML Notation . . . . . . . . . . . . . . . . . 21 19. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 20. Security Considerations . . . . . . . . . . . . . . . . . . . 23 21. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 21.1. Normative References . . . . . . . . . . . . . . . . . . 23 21.2. Informative References . . . . . . . . . . . . . . . . . 23 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 24 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 24 Freytag Informational [Page 2] RFC 8228 Variant Rules August 2017 1. Introduction Label Generation Rulesets (LGRs) that define the set of permissible labels may be applied to identifier systems that rely on labels, such as the Domain Name System (DNS) [RFC1034] [RFC1035]. To date, LGRs have mostly been used to define policies for implementing Internationalized Domain Names (IDNs) using IDNA2008 [RFC5890] [RFC5891] [RFC5892] [RFC5893] [RFC5894] in the DNS. This document aims to discuss the generation of LGRs for such circumstances, but the techniques and considerations here are almost certainly applicable to a wider range of internationalized identifiers.Show full document text