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Copyright (C) The Internet Society (2001). All Rights Reserved.

Abstract

This document describes a URN (Uniform Resource Name) namespace that is designed to allow Public Identifiers to be expressed in URI (Uniform Resource Identifiers) syntax.

この文書は、公開識別子を URI (Uniform Resource Identifiers) 構文で表現するための URN (Uniform Resource Name) 名前空間を説明します。

1. Introduction

XML [1] external entities have two identifiers: a system identifier and a public identifier. The system identifier is a URI, by definition, but the public identifier is simply a string.

XML 外部実体は、システム識別子と公開識別子の2つの識別子を持ちます。 システム識別子は URI として定義されており、 一方公開識別子は単なる文字列です。

Historically, the system identifier of an external entity has been a local, or system-specific identifier while the public identifier has been a more global, persistent name.

歴史的には、外部実体のシステム識別子はlocal或いはシステム規定の識別子で、他方公開識別子はよりglobalで永続的な名前です。

Unfortunately, public identifiers do not fit neatly into the existing web architecture because they are not legal URIs. Many new specifications (XSLT, XML Schema, etc.) have the implicit or explicit requirement that all external identifiers be URIs.

不幸にも、公開識別子は妥当な URI でないために既存のwebarchitectureにあまり適応しません。 多くの新しい仕様書 (XSLT, XMLSchema など) が陽に陰に、全ての外部識別子が URI であることを求めています。

The purpose of this namespace is to allow public identifiers to be encoded in URNs in a reliable, comparable way.

この名前空間の目的は、公開識別子を信頼可能で比較可能な方法で URN を符号化することを可能とすることです。

This document describes a scheme for representing public identifiers as URNs by introducing a public identifier namespace, "publicid".

この文書は、公開識別子名前空間 pubid を導入することで公開識別子を URN として表現する枠組みを説明します。

This namespace specification is for a formal namespace.

この名前空間仕様は公式名前空間のものです。

2. Specification Template 仕様雛形

   Namespace ID:

      "publicid" requested.

   Registration Information:

      Registration Version Number: 1
      Registration Date: 2001-05-08

   Declared registrant of the namespace:

      Norman Walsh
      Sun Microsystems, Inc.
      One Network Drive MS UBURO2-201
      Burlington, MA
      01803-0902

      Norman.Walsh@East.Sun.COM

   Declaration of structure:

The Namespace Specific String (NSS) for URNs in the "publicid" namespace has the following structure:

URN の publicid 名前空間 の名前空間規定文字列 (NSS) は次の構造を持ちます。

         urn:publicid:{transcribed-public-identifier}

Where:

{transcribed-public-identifier} is the text of the public identifier transcribed according to the following rules:

ここで、

{transcribed-public-identifier} は次の規則で公開識別子を書き直した文です。

               -  A space in the public identifier is transcribed as
                  "+".  Whitespace normalization must be performed
                  before constructing a URN in the "publicid" namespace,
                  therefore adjacent "+" characters never occur in URNs
                  in this namespace.
               -  The sequence of characters "//" is transcribed as ":".
               -  The sequence of characters "::" is transcribed as ";".
               -  A literal "+" character is transcribed as "%2B".
               -  A literal ":" character (except in "::") is
                  transcribed as "%3A".
               -  A literal "/" character (except in "//") is
                  transcribed as "%2F".
               -  A literal ";" character is transcribed as "%3B".
               -  A literal "'" character is transcribed as "%27".
               -  A literal "?" character is transcribed as "%3F".
               -  A literal "#" character is transcribed as "%23".
               -  A literal "%" character is transcribed as "%25".

1. 公開識別子中の間隔を + に書き直す。 publicid 名前空間の URN への変換前に正規化が行われているはずなので、 この名前空間では + が隣接することはない。
2. 文字列 // は : に書き直す。
3. 文字列 :: は ; に書き直す。
4. literal + 文字は %2B に書き換える。
5. literal : 文字 (:: を除く。) は %3A に書き換える。
6. literal / 文字 (// を除く。) は %2F に書き換える。
7. literal ; 文字は %3B に書き換える。
8. literal ' 文字は %27 に書き換える。
9. literal ? 文字は %3F に書き換える。
10. literal # 文字は %23 に書き換える。
11. literal % 文字は %25 に書き換える。

The special rules for "//" and "::" are designed to preserve the structured nature of formal public identifiers without requiring the translator to have special knowledge of FPI syntax.

// 及び :: の特別な規則は、公式公開識別子の構造化された性質を、 翻訳者に FPI 構文についての特別な知識を要求すること無しに保持するために設計されました。

The rules for "+", ":", "/", and ";" are required to preserve literal occurrences of these characters in the 'publicid' URN namespace.

+, :, /, ; の規則は publicid URN 名前空間内でこれらの文字のliteralな出現を防ぐために必要です。

The remaining characters, " " (space), "'", "?", "#", and "%", are the only other legal characters in public identifiers that cannot be literally transcribed into a URN by the rules of RFC 2141 [4] and RFC 2396 [5].

残りの文字、 (間隔), ', ?, #, % は RFC2141 及び RFC2396 の規則により URN 中でliteralに記述することができないものの公開識別子中では合法なほかの文字です。

   Relevant ancillary documentation:

      Extensible Markup Language (XML) Version 1.0 Second Edition [1]
      Standard Generalized Markup Language (SGML) [2]
      Registration procedures for public text owner identifiers [3]

   Identifier uniqueness considerations:

The identifier uniqueness considerations for URNs in the "publicid" namespace are the same as the identifier uniqueness considerations for public identifiers. Formal Public Identifiers with registered owner identifiers are required to be unique. For unregistered owner identifiers and informal public identifiers, they may or may not be unique. No enforcement policy can be asserted.

publicid 名前空間の URI の識別子唯一性についての考察は、 公開識別子の識別子唯一性についての考察と同じです。 固有性の保証のためには登録所有者識別子を使った公式公開識別子が必要です。 未登録所有者識別子及び非公式公開識別子については、 唯一であるかもしれないしないかもしれません。 特に強制する方針はありません。

   Identifier persistence considerations:

The persistence of URNs in the "publicid" namespace is the same as the persistence of the corresponding public identifier.

publicid 名前空間の URI の永続性は、 対応する公開識別子の永続性と同じです。

The "publicid" namespace is available for a wide range of uses; it cannot be subjected to a uniform persistence policy. As a general rule, formal public identifiers with registered owner identifiers are more likely to be persistent than informal public identifiers or formal public identifiers with unregistered owner identifiers.

publicid 名前空間は広範囲の使用に利用できます。 これはuniform永続性方針の対象とすることが出来ません。 一般的規則の通り、登録所有者識別子による公式公開識別子は非公式公開識別子や未登録所有者識別子による公式公開識別子より永続的でしょう。

One exception to this rule is the "IDN" scheme for producing a registered owner identifier from a domain name. That scheme contains at least all the weaknesses associated with the persistence of domain names.

この規則の一つの例外は、ドメイン名から生成される登録所有者識別子の枠組み IDN です。 この枠組みは、少なくてもドメイン名の永続性に関する全ての弱さを含み持ちます。

It is important to note that a properly registered owner identifier can apply any policy desired to the portion of the "publicid" URN namespace identified by that owner identifier.

適当な登録所有者識別子は、その所有者識別子で識別される publicid URN 名前空間の部分に望まれるどんな方針も適用できることに注意するのは重要です。

   Process of identifier assignment:

      Identifiers in the "publicid" namespace are assigned by applying
      the conversions described above to a public identifier.  In order
      to provide a URN in this namespace for a resource that does not
      have a public identifier, one must be created (according to the
      rules for creating public identifiers).

      There is no requirement that a resource have only one public
      identifier.

   Process of identifier resolution:

      Identifiers in the "publicid" namespace may be resolved by the
      same policies and procedures as public identifiers.  Public
      identifiers can be resolved in many different ways.  Many existing
      systems provide facilities for resolving them by way of OASIS
      TR9401 [6] Catalog files.  Other systems resolve them by mapping
      each component to a local pathname component.  And some systems
      simply "know about" a fixed set of public identifiers.  In
      addition, URNs in the 'publicid' namespace may be resolvable by
      other mechanisms unique to URIs (such as caches).

   Rules for Lexical Equivalence:

      Whitespace normalization is performed before constructing a URN in
      the "publicid" namespace, so URNs are lexically equivalent if and
      only if they are lexically identical.

   Conformance with URN Syntax:

      No special considerations.  URNs in this namespace conform to both
      RFC 2141 and RFC 2396.

   Validation mechanism:

      None specified.

   Scope:

      Global

3. Examples 例

The following examples are not guaranteed to be real. They are listed for pedagogical reasons only.

次の例は実在することを保証しません。 これらは説明のために挙げただけです。

      "ISO/IEC 10179:1996//DTD DSSSL Architecture//EN" becomes
      "urn:publicid:ISO%2FIEC+10179%3A1996:DTD+DSSSL+Architecture:EN"

      "ISO 8879:1986//ENTITIES Added Latin 1//EN" becomes
      "urn:publicid:ISO+8879%3A1986:ENTITIES+Added+Latin+1:EN"

      "-//OASIS//DTD DocBook XML V4.1.2//EN" becomes
      "urn:publicid:-:OASIS:DTD+DocBook+XML+V4.1.2:EN"

      "+//IDN example.org//DTD XML Bookmarks 1.0//EN//XML" becomes
      "urn:publicid:%2B:IDN+example.org:DTD+XML+Bookmarks+1.0:EN:XML"

      "-//ArborText::prod//DTD Help Document::19970708//EN" becomes
      "urn:publicid:-:ArborText;prod:DTD+Help+Document;19970708:EN"

      "foo" becomes
      "urn:publicid:foo"

      "3+3=6" becomes
      "urn:publicid:3%2B3=6"

      "-//Acme, Inc.//DTD Book Version 1.0" becomes
      "urn:publicid:-:Acme,+Inc.:DTD+Book+Version+1.0"

4. Security Considerations

      There are no additional security considerations other than those
      normally associated with the use and resolution of URNs in
      general.

References

   [1]   W3C, XML WG, "Extensible Markup Language (XML) 1.0 Second
         Edition", February 1998, http://www.w3.org/TR/REC-xml.

   [2]   JTC 1, SC 34, "ISO 8879:1986 Information processing -- Text and
         office systems -- Standard Generalized Markup Language (SGML)",
         1986.

   [3]   JTC 1, SC 34, "ISO/IEC 9070:1991 Information technology -- SGML
         support facilities -- Registration procedures for public text
         owner identifiers", 1991.

   [4]   Moats, R., "URN Syntax", RFC 2141, May 1997.

   [5]   Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
         Resource Identifiers (URI): Generic Syntax", RFC 2396, August
         1998.

   [6]   Grosso, P., "Entity Management: OASIS Technical Resolution
         9401:1997 (Amendment 2 to TR 9401)", Sep 1997,
         http://www.oasis-open.org/html/tr9401.html.

Authors' Addresses

   Norman Walsh
   Sun Microsystems, Inc.
   One Network Drive MS UBURO2-201
   Burlington, MA  01803-0902
   US

   EMail: Norman.Walsh@East.Sun.COM

   John Cowan
   Reuters Health Information
   45 West 36th St, 12th Floor
   New York, NY  10018
   US

   EMail: jcowan@reutershealth.com

   Paul Grosso
   Arbortext, Inc.
   1000 Victors Way
   Ann Arbor, MI  48108-2744
   US

   EMail: pgrosso@arbortext.com

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