'''Internationalized Resource Identifiers (IRIs)'''
-Network Working Group                                         
-Request for Comments: 3987                                          
-Category: Standards Track                                   
- M. Duerst
- W3C
- M. Suignard
-                                                   Microsoft Corporation
-                                                            January 2005

*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

* メモ