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Internationalized Resource Identifiers (IRIs)
RFC 3987

Document type: RFC - Proposed Standard (January 2005; Errata)
Was draft-duerst-iri (individual in app area)
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 3987 (Proposed Standard)
Responsible AD: Ted Hardie
Send notices to: <mduerst@w3.org>, <michelsu@microsoft.com>

Network Working Group                                          M. Duerst
Request for Comments: 3987                                           W3C
Category: Standards Track                                    M. Suignard
                                                   Microsoft Corporation
                                                            January 2005

             Internationalized Resource Identifiers (IRIs)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document defines a new protocol element, the Internationalized
   Resource Identifier (IRI), as a complement to the Uniform Resource
   Identifier (URI).  An IRI is a sequence of characters from the
   Universal Character Set (Unicode/ISO 10646).  A mapping from IRIs to
   URIs is defined, which means that IRIs can be used instead of URIs,
   where appropriate, to identify resources.

   The approach of defining a new protocol element was chosen instead of
   extending or changing the definition of URIs.  This was done in order
   to allow a clear distinction and to avoid incompatibilities with
   existing software.  Guidelines are provided for the use and
   deployment of IRIs in various protocols, formats, and software
   components that currently deal with URIs.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
       1.1.  Overview and Motivation  . . . . . . . . . . . . . . . .  3
       1.2.  Applicability  . . . . . . . . . . . . . . . . . . . . .  3
       1.3.  Definitions  . . . . . . . . . . . . . . . . . . . . . .  4
       1.4.  Notation . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  IRI Syntax . . . . . . . . . . . . . . . . . . . . . . . . . .  6
       2.1.  Summary of IRI Syntax  . . . . . . . . . . . . . . . . .  6
       2.2.  ABNF for IRI References and IRIs . . . . . . . . . . . .  7

Duerst & Suignard           Standards Track                     [Page 1]
RFC 3987         Internationalized Resource Identifiers     January 2005

   3.  Relationship between IRIs and URIs . . . . . . . . . . . . . . 10
       3.1.  Mapping of IRIs to URIs  . . . . . . . . . . . . . . . . 10
       3.2.  Converting URIs to IRIs  . . . . . . . . . . . . . . . . 14
             3.2.1.  Examples . . . . . . . . . . . . . . . . . . . . 15
   4.  Bidirectional IRIs for Right-to-Left Languages.  . . . . . . . 16
       4.1.  Logical Storage and Visual Presentation  . . . . . . . . 17
       4.2.  Bidi IRI Structure . . . . . . . . . . . . . . . . . . . 18
       4.3.  Input of Bidi IRIs . . . . . . . . . . . . . . . . . . . 19
       4.4.  Examples . . . . . . . . . . . . . . . . . . . . . . . . 19
   5.  Normalization and Comparison . . . . . . . . . . . . . . . . . 21
       5.1.  Equivalence  . . . . . . . . . . . . . . . . . . . . . . 22
       5.2.  Preparation for Comparison . . . . . . . . . . . . . . . 22
       5.3.  Comparison Ladder  . . . . . . . . . . . . . . . . . . . 23
             5.3.1.  Simple String Comparison . . . . . . . . . . . . 23
             5.3.2.  Syntax-Based Normalization . . . . . . . . . . . 24
             5.3.3.  Scheme-Based Normalization . . . . . . . . . . . 27
             5.3.4.  Protocol-Based Normalization . . . . . . . . . . 28
   6.  Use of IRIs  . . . . . . . . . . . . . . . . . . . . . . . . . 29
       6.1.  Limitations on UCS Characters Allowed in IRIs  . . . . . 29
       6.2.  Software Interfaces and Protocols  . . . . . . . . . . . 29
       6.3.  Format of URIs and IRIs in Documents and Protocols . . . 30
       6.4.  Use of UTF-8 for Encoding Original Characters .. . . . . 30
       6.5.  Relative IRI References  . . . . . . . . . . . . . . . . 32
   7.  URI/IRI Processing Guidelines (informative)  . . . . . . . . . 32
       7.1.  URI/IRI Software Interfaces  . . . . . . . . . . . . . . 32
       7.2.  URI/IRI Entry  . . . . . . . . . . . . . . . . . . . . . 33
       7.3.  URI/IRI Transfer between Applications  . . . . . . . . . 33
       7.4.  URI/IRI Generation . . . . . . . . . . . . . . . . . . . 34
       7.5.  URI/IRI Selection  . . . . . . . . . . . . . . . . . . . 34
       7.6.  Display of URIs/IRIs . . . . . . . . . . . . . . . . . . 35
       7.7.  Interpretation of URIs and IRIs  . . . . . . . . . . . . 36
       7.8.  Upgrading Strategy . . . . . . . . . . . . . . . . . . . 36
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 37
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 39

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