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.

この文書は新しいプロトコル要素、 国際化資源識別子 (IRI) を統一資源識別子 (URI) を補完するものとして定義します。 IRI は普遍文字集合 (Unicode / ISO/IEC 10646) の文字の列です。 IRI から URI への写像を定義しますが、これは IRI を適当なところで URI の代わりに資源の識別のために使えることを意味します。

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.

新しいプロトコル要素を定義するという方法を URI の定義を拡張したり変更したりする方法の代わりとして選びました。 これは明確な区別を可能とし、既存のソフトウェアとの非互換性を避けるためです。 現在 URI を処理している色々なプロトコル、書式、ソフトウェア部品で IRI を使用・採用するための指針も提供しています。

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
   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
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40
       10.1. Normative References . . . . . . . . . . . . . . . . . . 40
       10.2. Informative References . . . . . . . . . . . . . . . . . 41
   A.  Design Alternatives  . . . . . . . . . . . . . . . . . . . . . 44
       A.1.  New Scheme(s)  . . . . . . . . . . . . . . . . . . . . . 44
       A.2.  Character Encodings Other Than UTF-8 . . . . . . . . . . 44
       A.3.  New Encoding Convention  . . . . . . . . . . . . . . . . 44
       A.4.  Indicating Character Encodings in the URI/IRI  . . . . . 45
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 45
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 46