Right-to-Left Scripts for Internationalized Domain Names for Applications (IDNA)
RFC 5893
| Document | Type | RFC - Proposed Standard (August 2010; No errata) | |
|---|---|---|---|
| Authors | Cary Karp , Harald Alvestrand | ||
| Last updated | 2015-10-14 | ||
| Replaces | draft-alvestrand-idna-bidi | ||
| Stream | Internent Engineering Task Force (IETF) | ||
| Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5893 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Lisa Dusseault | ||
| Send notices to | (None) | ||
Internet Engineering Task Force (IETF) H. Alvestrand, Ed.
Request for Comments: 5893 Google
Category: Standards Track C. Karp
ISSN: 2070-1721 Swedish Museum of Natural History
August 2010
Right-to-Left Scripts for
Internationalized Domain Names for Applications (IDNA)
Abstract
The use of right-to-left scripts in Internationalized Domain Names
(IDNs) has presented several challenges. This memo provides a new
Bidi rule for Internationalized Domain Names for Applications (IDNA)
labels, based on the encountered problems with some scripts and some
shortcomings in the 2003 IDNA Bidi criterion.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
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/rfc5893.
Copyright Notice
Copyright (c) 2010 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.
Alvestrand & Karp Standards Track [Page 1]
RFC 5893 IDNA Right to Left August 2010
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Purpose and Applicability . . . . . . . . . . . . . . . . 2
1.2. Background and History . . . . . . . . . . . . . . . . . . 3
1.3. Structure of the Rest of This Document . . . . . . . . . . 3
1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. The Bidi Rule . . . . . . . . . . . . . . . . . . . . . . . . 6
3. The Requirement Set for the Bidi Rule . . . . . . . . . . . . 6
4. Examples of Issues Found with RFC 3454 . . . . . . . . . . . . 9
4.1. Dhivehi . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. Yiddish . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.3. Strings with Numbers . . . . . . . . . . . . . . . . . . . 12
5. Troublesome Situations and Guidelines . . . . . . . . . . . . 12
6. Other Issues in Need of Resolution . . . . . . . . . . . . . . 13
7. Compatibility Considerations . . . . . . . . . . . . . . . . . 14
7.1. Backwards Compatibility Considerations . . . . . . . . . . 14
7.2. Forward Compatibility Considerations . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . . 17
1. Introduction
1.1. Purpose and Applicability
The purpose of this document is to establish a rule that can be
applied to Internationalized Domain Name (IDN) labels in Unicode form
(U-labels) containing characters from scripts that are written from
right to left. It is part of the revised IDNA protocol [RFC5891].
When labels satisfy the rule, and when certain other conditions are
satisfied, there is only a minimal chance of these labels being
displayed in a confusing way by the Unicode bidirectional display
algorithm.
The other normative documents in the IDNA2008 document set establish
criteria for valid labels, including listing the permitted
characters. This document establishes additional validity criteria
for labels in scripts normally written from right to left.
This specification is not intended to place any requirements on
domain names that do not contain characters from such scripts.
Alvestrand & Karp Standards Track [Page 2]
RFC 5893 IDNA Right to Left August 2010
1.2. Background and History
The "Stringprep" specification [RFC3454], part of IDNA2003, made the
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