171.txt

;; [1] [CODE(URI)@en[[[info:]]]] も参照。

Network Working Group                                   H. Van de Sompel
Request for Comments: 4452                                          LANL
Category: Informational                                       T. Hammond
[PRE[
                                                                     NPG
                                                               E. Neylon
                                                      Manifest Solutions
                                                               S. Weibel
                                                                    OCLC
                                                              April 2006
]PRE]

[PRE[
                         The "info" URI Scheme
      for Information Assets with Identifiers in Public Namespaces
]PRE]

Status of This Memo

[PRE[
   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.
]PRE]

Copyright Notice

[PRE[
   Copyright (C) The Internet Society (2006).
]PRE]


* Abstract

[PRE[
   This document defines the "info" Uniform Resource Identifier (URI)
   scheme for information assets with identifiers in public namespaces.
   Namespaces participating in the "info" URI scheme are regulated by an
   "info" Registry mechanism.
]PRE]

この文書は、公開名前空間の識別子により[[情報資産]]を識別する
[CODE(URI)@en[[[info]]]] [[統一資源識別子]] ([[URI]])
scheme を定義します。
[CODE(URI)@en[[[info]]]] [[URI scheme]]
に属する[[名前空間]]は [CODE(URI)@en[[[info]]]]
登録簿機構が統制します。


* Table of Contents

[PRE[
   1. Introduction ....................................................3
      1.1. Terminology ................................................3
      1.2. Information Assets .........................................3
   2. Application of the "info" URI Scheme ............................4
   3. The "info" Registry .............................................5
      3.1. Management Characteristics of the "info" Registry ..........5
      3.2. Functional Characteristics of the "info" Registry ..........5
      3.3. Maintenance of the "info" Registry .........................6
   4. The "info" URI Scheme ...........................................6
      4.1. Definition of "info" URI Syntax ............................6
      4.2. Allowed Characters Under the "info" URI Scheme .............8
      4.3. Examples of "info" URIs ....................................9
   5. Normalization and Comparison of "info" URIs ....................10
   6. Rationale ......................................................12
      6.1. Why Create a New URI Scheme for Identifiers from Public
           Namespaces? ...............................................12
      6.2. Why Not Use an Existing URI Scheme for Identifiers
           from Public Namespaces? ...................................12
      6.3. Why Not Create a New URN Namespace ID for
           Identifiers from Public Namespaces? .......................12
   7. Security Considerations ........................................13
   8. IANA Considerations ............................................14
   9. Acknowledgements ...............................................14
   10. References ....................................................14
      10.1. Normative References .....................................14
      10.2. Informative References ...................................15
]PRE]


* 1.  Introduction

[PRE[
   This document defines the "info" Uniform Resource Identifier (URI)
   scheme for information assets that have identifiers in public
   namespaces but are not part of the URI allocation.  By "information
   asset" this document intends any information construct that has
   identity within a public namespace.
]PRE]

この文書は、公開名前空間に識別子を持つものの [[URI]]
割当の対象となっていない[[情報資産]]のための [CODE(URI)@en[[[info]]]]
[[統一資源識別子]] ([[URI]]) scheme を定義します。
この文書において[DFN[[[情報資産]]]]とは、
公開名前空間中で識別される情報構造を指します。


** 1.1.  Terminology

[PRE[
   In this document, the keywords "MUST", "MUST NOT", "SHALL", "SHALL
   NOT", "SHOULD", "SHOULD NOT", "MAY", "MAY NOT", and "RECOMMENDED" are
   to be interpreted as described in RFC 2119 [RFC2119] and indicate
   requirement levels for compliant implementations.
]PRE]


** 1.2.  Information Assets

[PRE[
   There exist many information assets with identifiers in public
   namespaces that are not referenceable by URI schemes.  Examples of
   such namespaces include Dewey Decimal Classifications [DEWEY],
   Library of Congress Control Numbers [LCCN], NISO Serial Item and
   Contribution Identifiers [SICI], NASA Astrophysics Data System
   Bibcodes [BIBCODE], and National Library of Medicine PubMed
   identifiers [PMID].  Other candidate namespaces include Online
   Computer Library Center OCLC Numbers [OCLCNUM] and NISO OpenURL
   Framework identifiers [OFI].
]PRE]

公開名前空間中の識別子を持つ、 [[URI scheme]] 
により参照可能でない[[情報資産]]は多く存在します。
そのような名前空間の例としては、 [[デューイ十進分類法]]、
[[米国議会図書館管理番号]]、[[NISO逐次刊行物及び寄稿識別子]]、
[[NASA宇宙物理学データ・システム書誌符号]]、
[[米国国立医学図書館PubMed識別子]]などがあります。
その他の名前空間の候補としては、
[[オンライン計算機図書館センター]] [[PCLC番号]]や
[[NISO]] [[OpenURL枠組識別子]]があります。

[PRE[
   The "info" URI scheme facilitates the referencing of information
   assets that have identifiers in such public namespaces by means of
   URIs.  When referencing an information asset by means of its "info"
   URI, the asset SHALL be considered a "resource" as defined in RFC
   3986 [RFC3986] and SHALL enjoy the same common syntactic, semantic,
   and shared language benefits that the URI presentation confers.  As
   such, the "info" URI scheme enables public namespaces that are not
   part of the URI allocation to be represented within the allocation.
   The "info" URI scheme thus provides a bridging mechanism to allow
   public namespaces to become part of the URI allocation.
]PRE]

[CODE(URI)@en[[[info]]]] [[URI scheme]] は、
このような公開名前空間に識別子を持つ[[情報資産]]の [[URI]]
による参照を促進します。[[情報資産]]をその [CODE(URI)@en[[[info]]]]
[[URI]] により参照する時は、その[[情報資産]]は [[RFC 3986]]
で定義された[Q[[[資源]]]]と考慮し[['''なければなりません''']]し、
[[URI]] 表現により与えられる同じ共通の構文的、意味的、
そして共通言語の利益を享受し[['''なければなりません''']]。
ですから、 [CODE(URI)@en[[[info]]]] [[URI scheme]]
は [[URI]] が割当てられていなかった公開名前空間に [[URI]]
を割当てて使用することを可能とします。従いまして、 [CODE(URI)@en[[[info]]]]
[[URI scheme]] は公開名前空間が [[URI]] 割当の一部となるような橋梁機構を提供します。

[PRE[
   Namespaces declared under the "info" URI scheme are regulated by an
   "info" Registry mechanism.  The "info" Registry allows a public
   namespace that is not part of the URI allocation to be declared in a
   registration process by the organization that manages it (the
   Namespace Authority).  The "info" Registry supports the declaration
   of public namespaces that are not part of the URI allocation in a
   manner that facilitates the construction of URIs for information
   assets without imposing the burdens of independent URI registration
   and maintenance of resource representations on the Namespace
   Authority.  Information assets identified within a registered
   namespace SHALL be added or deleted according to the business
   processes of the Namespace Authority, and yet MAY be referenced
   within network applications via the "info" URI in an open,
   standardized way without additional action on the part of the
   Namespace Authority.
]PRE]

[PRE[
   The "info" URI scheme exists primarily for identification purposes.
   Implementations MUST NOT assume that an "info" URI can be
   dereferenced to a representation of the resource identified by the
   URI although Namespace Authorities MAY disclose in the registration
   record references to service mechanisms pertaining to identifiers
   from the registered namespace.  Applications of the "info" URI scheme
   are restricted to the identification of information assets and the
   declaration of normalization rules for comparing identifiers of such
   information assets regardless of whether any services relating to
   such information assets are accessible via the Internet.  References
   to such services MAY be disclosed within an "info" registration
   record, but these services SHALL NOT be regarded as authoritative.
   The "info" URI scheme does not support global resolution methods.
]PRE]


* 2.  Application of the "info" URI Scheme

[PRE[
   Public namespaces that are used for the identification of information
   assets and that are not part of the URI allocation MAY be registered
   as namespaces within the "info" Registry.  Namespace Authorities MAY
   register these namespaces in the "info" Registry, thereby making
   these namespaces available to applications that need to reference
   information assets by means of a URI.  Registrations of public
   namespaces that are not part of the URI allocation by parties other
   than the Namespace Authority SHALL NOT be permitted, thereby ensuring
   against hostile usurpation or inappropriate usage of registered
   service marks or the public namespaces of others.
]PRE]

[PRE[
   Registration of a public namespace under the "info" Registry implies
   no particular functionalities of the identifiers from the registered
   namespace other than the identification of information assets.  No
   resolution mechanisms can be assumed for the "info" URI scheme,
   though for any particular namespace there MAY exist mechanisms for
   resolving identifiers to network services.  The definition of such
   services falls outside the scope of the "info" URI scheme.
   Registration does not define namespace-specific semantics for
   identifiers within a registered namespace, though allowable character
   sets and normalization rules are specified in Sections 4 and 5 so as
   to ensure that the URIs created using such identifiers are compliant
   with applications that use URIs.
]PRE]

Van de Sompel, et al.        Informational                      [Page 4]
[PRE[

RFC 4452                 The "info" URI Scheme                April 2006
]PRE]

[PRE[
   The registration of a public namespace in the "info" Registry SHALL
   NOT preclude further development of services associated with that
   namespace that MAY qualify the namespace for additional publication
   elsewhere within the URI allocation.
]PRE]

3.  The "info" Registry

[PRE[
   The "info" Registry provides a mechanism for the registration of
   public namespaces that are used for the identification of information
   assets and that are not part of the URI allocation.
]PRE]

[PRE[
   NISO [NISO], the National Information Standards Organization, will
   act as the Maintenance Agency for the "info" Registry and will
   delegate the day-to-day operation of the "info" Registry to a
   Registry Operator.  As the Maintenance Agency, NISO will ensure that
   the Registry Operator operates the "info" Registry in accordance with
   a publicly articulated policy document established under NISO
   governance and made available on the "info" website,
   <http://info-uri.info/>.  The "info" Registry policy defines a review
   process for candidate namespaces and provides measures of quality
   control and suitability for entry of namespaces.
]PRE]

3.1.  Management Characteristics of the "info" Registry

[PRE[
   The "info" Registry will be managed according to policies established
   under the auspices of NISO.  All such policies, as well as the
   namespace declarations in the "info" Registry, will be public.
]PRE]

3.2.  Functional Characteristics of the "info" Registry

[PRE[
   The "info" Registry will be publicly accessible and will support
   discovery (by both humans and machines) of:
]PRE]

[PRE[
   o  string literals identifying the namespaces for which the Registry
      provides a guarantee of uniqueness and persistence
   o  names and contact information of Namespace Authorities
   o  syntax requirements for identifiers maintained in such namespaces
   o  normalization methodologies for identifiers maintained in such
      namespaces
   o  network references to a description of service mechanisms (if any)
      for identifiers maintained in such namespaces
   o  ancillary documentation
]PRE]

[PRE[
   Registry entries refer to the corresponding "namespace" and
   "identifier" components, which are defined in the ABNF given in
   Section 4.1 of this document.
]PRE]

Van de Sompel, et al.        Informational                      [Page 5]
[PRE[

RFC 4452                 The "info" URI Scheme                April 2006
]PRE]

3.3.  Maintenance of the "info" Registry

[PRE[
   The public namespaces that MAY be registered in the "info" Registry
   will be those of interest to the communities served by NISO, and
   therefore NISO is committed to act as Maintenance Authority for the
   "info" Registry and to assign a Registry Operator to operate it.
]PRE]

[PRE[
   NISO, a non-profit association accredited by the American National
   Standards Institute (ANSI), identifies, develops, maintains, and
   publishes technical standards to manage information in the digital
   environment.  NISO standards apply technologies to the full range of
   information-related needs, including retrieval, re-purposing,
   storage, metadata, and preservation.
]PRE]

[PRE[
   Founded in 1939, incorporated as a not-for-profit education
   association in 1983, and assuming its current name the following
   year, NISO draws its support from the communities it serves.  The
   leaders of over 70 organizations in the fields of publishing,
   libraries, IT, and media serve as its voting members.  Hundreds of
   experts and practitioners serve on NISO committees and as officers of
   the association.
]PRE]

[PRE[
   NISO has been designated by ANSI to represent US interests to the
   International Organization for Standardization's (ISO) Technical
   Committee 46 on Information and Documentation.
]PRE]

[PRE[
   The NISO headquarters office is located at 4733 Bethesda Ave.,
   Bethesda, MD 20814, USA.  (For further information, see the NISO
   website, <http://www.niso.org/>.)
]PRE]


* 4.  The "info" URI Scheme


** 4.1.  Definition of "info" URI Syntax

[PRE[
   The "info" URI syntax presented in this document is conformant with
   the generic URI syntax defined in RFC 3986 [RFC3986].  This
   specification uses the Augmented Backus-Naur Form (ABNF) notation of
   RFC 4234 [RFC4234] to define the URI.  The following core ABNF
   productions are used by this specification as defined by Appendix B.1
   of RFC 4234: ALPHA, DIGIT, HEXDIG.
]PRE]

[2] この文書に示す [CODE(URI)@en[[[info]]]] [[URI]] 構文は [[RFC 3986]]
で定義された共通 [[URI]] 構文に[[適合]]します。
この仕様書は [[URI]] を定義するために [[RFC 4234]] の[[増補バッカス・ナウア形式]]
([[ABNF]]) 記法を使います。 [[RFC 4234]] の附属書 B.1
で定義されている中核 [[ABNF]] [[生成規則]]
[CODE(ABNF)@en[[[ALPHA]]]]、[CODE(ABNF)@en[[[DIGIT]]]]、
[CODE(ABNF)@en[[[HEXDIG]]]] を使います。

[PRE[
   The "info" URI syntax is presented in two parts.  Part A contains
   productions specific to the "info" URI scheme, while Part B contains
   generic productions from RFC 3986 [RFC3986], which are repeated here
   both for completeness and for reference.  The following set of
   productions (Part A) is specific to the "info" URI scheme:
]PRE]

[CODE(URI)@en[[[info]]]] [[URI]] 構文は二部に分けて示します。
A部は [CODE(URI)@en[[[info]]]] [[URI scheme]] に固有の[[生成規則]]です。
B部は [[RFC 3986]] にある共通の[[生成規則]]で、
完全性と参照のためにここに再録します。
次の[[生成規則]] (A部) は [CODE(URI)@en[[[info]]]]
[[URI scheme]] 固有のものです。

[PRE[
   ; Part A:
   ; productions specific to the "info" URI scheme
]PRE]

[PRE[
   info-URI        = info-scheme ":" info-identifier [ "#" fragment ]
]PRE]

[PRE[
   info-scheme     = "info"
]PRE]

[PRE[
   info-identifier = namespace "/" identifier
]PRE]

[PRE[
   namespace       = scheme
]PRE]

[PRE[
   identifier      = *( pchar / "/" )
]PRE]

[PRE[
   ; Note that "info" URIs containing dot-segments (i.e., segments
   ; whose full content consists of "." or "..") MAY NOT be suitable
   ; for use with applications that perform dot-segment normalization
]PRE]

;; [CODE(URI)@en[[[info]]]] [[URI]] は[[点分節]]
(つまり、内容全体が [CODE(URI)[[[.]]]] や [CODE(URI)[[[..]]]]
であるような[[分節]]) は[[点分節正規化]]を行う[[応用]]で使うのには適切と[['''してはいけません''']]。

[PRE[
   This next set of productions (Part B) are generic productions
   reproduced from RFC 3986 [RFC3986]:
]PRE]

次の[[生成規則]] (B部) は [[RFC 3986]] の共通の[[生成規則]]を再録したものです。

[PRE[
   ; Part B:
   ; generic productions from RFC 3986 [RFC3986]
]PRE]

[PRE[
   scheme          = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
]PRE]

[PRE[
   pchar           = unreserved / pct-encoded / sub-delims / ":" / "@"
]PRE]

[PRE[
   fragment        = *( pchar / "/" / "?" )
]PRE]

[PRE[
   unreserved      = ALPHA / DIGIT / "-" / "." / "_" / "~"
]PRE]

[PRE[
   pct-encoded     = "%" HEXDIG HEXDIG
]PRE]

[PRE[
   sub-delims      = "!" / "$" / "&" / "'" / "(" / ")"
                        / "*" / "+" / "," / ";" / "="
]PRE]

[PRE[
   An "info" URI has an "info-identifier" as its scheme-specific part
   and MAY take an optional "fragment" component.  An "info-identifier"
   is constructed by appending an "identifier" component to a
   "namespace" component separated by a slash "/" character.  The "info"
   URI scheme is supportive of hierarchical processing as indicated by
   the presence of the slash "/" character, although the slash "/"
   character SHOULD NOT be interpreted as a strict hierarchy delimiter.
]PRE]

scheme 固有部として [CODE(ABNF)@en[[[info-identifier]]]]
を持つ [CODE(URI)@en[[[info]]]] [[URI]] は、任意選択の
[CODE(URI)@en[[[fragment]]]] 部品を保持[['''して構いません''']]。
[CODE(ABNF)@en[[[info-identifier]]]] は、
[CODE(ABNF)@en[[[namespace]]]] 部品の後に[[斜線]] [CODE(URI)[[[/]]]]
[[文字]]と [CODE(ABNF)@en[[[identifier]]]] 部品を連結して構築します。
[CODE(URI)@en[[[info]]]] [[URI scheme]] は[[斜線]] [CODE(URI)@en[[[/]]]]
[[文字]]を使うことにより階層的な処理に支援的です。
ただし、[[斜線]] [CODE(URI)@en[[[/]]]] [[文字]]は厳密な階層区切りとして解釈[['''するべきではありません''']]。

[PRE[
   Values for the "namespace" component of the "info" URI are name
   tokens composed of URI scheme characters only (cf. the "scheme"
   production).  They identify the public namespace in which the
   (unescaped) value for the "identifier" component originates, and are
   registered in the "info" Registry, which guarantees their uniqueness
   and persistence.  Although the "namespace" component is
   case-insensitive, the canonical form is lowercase and documents that
   specify values for the "namespace" component SHOULD do so using
   lowercase letters.  An implementation SHOULD accept uppercase letters
   as equivalent to lowercase in "namespace" names, for the sake of
   robustness, but SHOULD only generate lowercase "namespace" names, for
   consistency.
]PRE]

[PRE[
   Values for the "identifier" component of the "info" URI MAY be viewed
   as being hierarchical strings composed of path segments built from
   path segment characters (cf. the "pchar" production), the segments
   being separated by slash "/" characters, although any semantic
   interpretation of the "/" character as a hierarchy delimiter MUST NOT
   be assumed.  In their originating public namespace, the (unescaped)
   values for the "identifier" component identify information assets.
   The values for the "identifier" component MUST be %-escaped as
   required by this syntax.  The "identifier" component SHOULD be
   treated as case-sensitive, although the "info" Registry MAY record
   the case-sensitivity of identifiers from particular registered public
   namespaces.  The "info" Registry MAY also disclose additional
   normalization rules regarding the treatment of punctuation characters
   and the like.
]PRE]

[PRE[
   Values for the "fragment" component of the "info" URI are strings
   composed of path segment characters (cf. the "pchar" production) plus
   the slash "/" character and the question mark "?" character.  No
   semantic role is assigned to the slash "/" character and the question
   mark "?" character within the "fragment" component.  The (unescaped)
   values for the "fragment" component identify secondary information
   assets with respect to the primary information asset, which is
   referenced by the "info-identifier".  The values for the "fragment"
   component MUST be %-escaped as required by this syntax.  The
   "fragment" component MUST be treated as being case-sensitive.
]PRE]


** 4.2.  Allowed Characters Under the "info" URI Scheme

[PRE[
   The "info" URI syntax uses the same set of allowed US-ASCII
   characters as specified in RFC 3986 [RFC3986] for a generic URI.  An
   "info" URI string SHOULD be represented as a Unicode [UNICODE] string
   and be encoded in UTF-8 [RFC3629] form.  Reserved characters as well
   as excluded US-ASCII characters and non-US-ASCII characters MUST be
   %-escaped before forming the URI.  Details of the %-escape encoding
   can be found in RFC 3986 [RFC3986], Section 2.4.
]PRE]


** 4.3.  Examples of "info" URIs

[PRE[
   Some examples of syntactically valid "info" URIs are given below:
]PRE]

[PRE[
       a) info:ddc/22/eng//004.678
]PRE]

[PRE[
   where "ddc" is the "namespace" component for a Dewey Decimal
   Classification [DEWEY] namespace and "22/eng//004.678" is the
   "identifier" component for an identifier of an information asset
   within that namespace.
]PRE]

[PRE[
   The information asset identified by the identifier "22/eng//004.678"
   in the namespace for (22nd Ed.)  English-language Dewey Decimal
   Classifications is the classification
]PRE]

[PRE[
       "Internet"
]PRE]

[PRE[
       b) info:lccn/2002022641
]PRE]

[PRE[
   where "lccn" is the "namespace" component for a Library of Congress
   Control Number [LCCN] namespace and "2002022641" is the "identifier"
   component for an identifier of an information asset within that
   namespace.
]PRE]

[PRE[
   The information asset identified by the identifier "2002022641" in
   the namespace for Library of Congress Control Numbers is the metadata
   record
]PRE]

[PRE[
       "Newcomer, Eric. Understanding Web services: XML, WSDL,
       SOAP, and UDDI. Boston: Addison-Wesley, 2002."
]PRE]

[PRE[
       c) info:sici/0363-0277(19950315)120:5%3C%3E1.0.TX;2-V
]PRE]

[PRE[
   where "sici" is the "namespace" component for a Serial Item and
   Contribution Identifier [SICI] namespace and
   "0363-0277(19950315)120:5%3C%3E1.0.TX;2-V" is the "identifier"
   component for an identifier of an information asset in that namespace
   in %-escaped form, or in unescaped form
   "0363-0277(19950315)120:5<>1.0.TX;2-V".
]PRE]

[PRE[
   The information asset identified by the identifier
   "0363-0277(19950315)120:5<>1.0.TX;2-V" in the namespace for Serial
   Item and Contribution Identifiers is the journal issue
]PRE]

[PRE[
       "Library Journal, Vol. 120, no. 5. March 15, 1995."
]PRE]

[PRE[
       d) <rdf:Description about="info:bibcode/2003Icar..163..263Z"/>
]PRE]

[PRE[
   where "bibcode" is the "namespace" component for a NASA Astrophysics
   Data System (ADS) Bibcode [BIBCODE] namespace and
   "2003Icar..163..263Z" is the "identifier" component for an identifier
   of an information asset within that namespace.  This example further
   shows an application of an "info" URI as the subject of a Resource
   Description Framework (RDF) statement.
]PRE]

[PRE[
   The information asset identified by the identifier
   "2003Icar..163..263Z" in the namespace for NASA ADS Bibcodes is the
   metadata record in the ADS system that describes the journal article
]PRE]

[PRE[
       "K. Zahnle, P. Schenk, H. Levison and L. Dones, Cratering rates
       in the outer Solar System, Icarus, 163 (2003) pp. 263-289."
]PRE]

[PRE[
       e) info:pmid/12376099
]PRE]

[PRE[
   where "pmid" is the "namespace" component for a PubMed Identifier
   [PMID] namespace and "12376099" is the "identifier" component for an
   identifier of an information asset in that namespace.
]PRE]

[PRE[
   The information asset identified by the identifier "12376099" in the
   namespace for PubMed Identifiers is the metadata record in the PubMed
   database that describes the journal article
]PRE]

[PRE[
       "Wijesuriya SD, Bristow J, Miller WL. Localization and analysis
       of the principal promoter for human tenascin-X. Genomics. 2002
       Oct;80(4):443-52."
]PRE]


* 5.  Normalization and Comparison of "info" URIs

[PRE[
   In order to facilitate comparison of "info" URIs, a sequence of
   normalization steps SHOULD be applied as detailed below.  After
   normalizing the URI strings, comparison of two "info" URIs is then
   applied on a character-by-character basis as prescribed by RFC 3986
   [RFC3986], Section 6.2.1.
]PRE]

[CODE(URI)@en[[[info]]]] [[URI]] の[[比較]]を容易にするために、
次に詳述する[[正規化]]の手順を適用[['''するべきです''']]。
[[URI]] 文字列の[[正規化]]の後に、2つの [CODE(URI)@en[[[info]]]]
[[URI]] に対して [[RFC 3986]] で説明されている[[文字]]毎の比較を適用します。

[PRE[
   The following generic normalization steps SHOULD anyway be applied by
   applications processing "info" URIs:
]PRE]

[CODE(URI)@en[[[info]]]] [[URI]] を処理する[[応用]]は、
いずれにせよ次の共通の[[正規化]]手順を適用[['''するべきです''']]。

[PRE[
        a) Normalize the case of the "scheme" component to be
           lowercase
        b) Normalize the case of the "namespace" component to be
           lowercase
        c) Unescape all unreserved %-escaped characters in the
           "namespace" and "identifier" components
        d) Normalize the case of any %-escaped characters in the
           "namespace" and "identifier" components to be
           uppercase
]PRE]

= [CODE(ABNF)@en[[[scheme]]]] 部品を[[小文字]]に[[正規化]]
= [CODE(ABNF)@en[[[namespace]]]] 部品を[[小文字]]に[[正規化]]
= [CODE(ABNF)@en[[[namespace]]]] 部品と [CODE(ABNF)@en[[[identifier]]]]
部品の[[百分率符号化]]された[[未予約文字]]をすべて[[復号]]
= [CODE(ABNF)@en[[[namespace]]]] 部品と [CODE(ABNF)@en[[[identifier]]]]
部品の[[百分率符号化]]された[[文字]]を[[大文字]]に[[正規化]]

[PRE[
   Further normalization steps MAY be applied by applications to "info"
   URIs based on rules recorded in the "info" Registry for a registered
   public namespace, but such normalization steps remain outside of the
   scope of the "info" URI definition.
]PRE]

[[応用]]は [CODE(URI)@en[[[info]]]] 登録簿で登録済み公開名前空間について記録されている規則に基づき
[CODE(URI)@en[[[info]]]] [[URI]] を更に[[正規化]][['''して構いません''']]が、
そのような[[正規化]]は [CODE(URI)@en[[[info]]]]
[[URI]] の定義の[[適用範囲]]外とします。

[PRE[
   Since the "info" URI SHOULD be treated as being case-sensitive, a
   canonical form MAY only be arrived at by consulting the "info"
   Registry for possible information on the case-sensitivity for
   identifiers from a registered public namespace, and any case
   normalization step to apply.  The "info" Registry MAY also disclose
   additional normalization rules regarding the treatment of punctuation
   characters and the like.
]PRE]

[CODE(URI)@en[[[info]]]] [[URI]]
は[[大文字・小文字を区別する]]ものと[['''するべきです''']]から、
登録済み公開名前空間の識別子が[[大文字]]・[[小文字]]を区別するかどうかの情報や[[大文字]]・[[小文字]]の[[正規化]]の方法についての情報は
[CODE(URI)@en[[[info]]]] 登録簿を調べることによりのみ到達[['''して構いません''']]。
[CODE(URI)@en[[[info]]]] [[登録簿]]は[[句読点文字]]等の取り扱いに関する[[正規化]]の規則についても公開[['''して構いません''']]。

[PRE[
   In cases, however, where no single canonical form of the "identifier"
   component exists, it is nevertheless RECOMMENDED that a Namespace
   Authority nominate a preferred form, which SHOULD be used wherever
   possible within an "info" URI so that applications MAY have an
   increased chance of successful comparison of two "info" URIs.
]PRE]

しかし、 [CODE(ABNF)@en[[[identifier]]]] 部品に単一の[[正準形]]が存在しない場合であっても、
[[名前空間当局者]]は優先形を指定することを[['''推奨''']]し、
可能であれば常に [CODE(URI)@en[[[info]]]] [[URI]]
ではその優先形を使用[['''するべきです''']]し、
そうすれば[[応用]]は2つの [CODE(URI)@en[[[info]]]] [[URI]]
の比較に成功する機会が増加[['''して構いません''']]。

[PRE[
   Note that "info" URIs containing dot-segments (i.e., segments whose
   full content consists of "." or "..") MAY NOT be suitable for use
   with applications that perform dot-segment normalization.
]PRE]

[[点分節]] (つまり、内容全体が [CODE(URI)[[[.]]]] または
[CODE(URI)[[[..]]]] である[[分節]]) を含む [CODE(URI)@en[[[info]]]] [[URI]]
は[[点分節正規化]]を行う[[応用]]で使うのに適切と[['''してはいけません''']]。

[PRE[
   The following unnormalized forms of an "info" URI
]PRE]

[PRE[
       U1. INFO:PII/S0888-7543(02)96852-7
       U2. info:PII/S0888754302968527
       U3. info:pii/S0888%2D7543%2802%2996852%2D7
       U4. info:pii/s0888-7543(02)96852-7
]PRE]

[PRE[
   are normalized to the following respective forms
]PRE]

[PRE[
       N1. info:pii/S0888-7543(02)96852-7
       N2. info:pii/S0888754302968527
       N3. info:pii/S0888-7543(02)96852-7
       N4. info:pii/s0888-7543(02)96852-7
]PRE]

[PRE[
   The "info" URI definition does not prescribe further normalization
   steps, although applications MAY apply additional normalization steps
   according to any rules recorded in the "info" Registry for a
   registered public namespace.
]PRE]


* 6.  Rationale


** 6.1.  Why Create a New URI Scheme for Identifiers from Public Namespaces?

[PRE[
   Under RFC 4395, "Guidelines and Registration Procedures for New URI
   Schemes" [RFC4395], it is stated in Section 2.1 "Demonstrable, New,
   Long-Lived Utility" that "New URI schemes SHOULD have clear utility
   to the broad Internet community, beyond that available with already
   registered URI schemes".  The "info" URI scheme allows identifiers
   within public namespaces, used for the identification of information
   assets, to be referred to within the URI allocation.  Once a
   namespace is registered in the "info" Registry, the "info" URI scheme
   enables an information asset with an identifier in that namespace to
   be referenced by means of a URI.  As a result, the information asset
   SHALL be considered a resource as defined in RFC 3986 [RFC3986] and
   SHALL enjoy the same common syntactic, semantic, and shared language
   benefits that the URI presentation confers.
]PRE]


** 6.2.  Why Not Use an Existing URI Scheme for Identifiers from Public Namespaces?

[PRE[
   Existing URI schemes are not suitable for employment as the "info"
   URI scheme admits of no global dereference mechanism.  While examples
   of resource identifiers minted under other URI schemes MAY not always
   be dereferenceable, nevertheless there is always a common expectation
   that such URIs can be dereferenced by various resolution mechanisms,
   whether they be location-dependent or location-independent resource
   identifiers.  The "info" URI scheme applies to a class of resource
   identifiers whose Namespace Authorities MAY or MAY NOT choose to
   disclose service mechanisms.  Nevertheless, Namespace Authorities are
   encouraged to disclose in the "info" registration record references
   to any such service mechanisms in order to provide a greater utility
   to network applications.
]PRE]


** 6.3.  Why Not Create a New URN Namespace ID for Identifiers from Public Namespaces?

[PRE[
   RFC 2141 [RFC2141] states that "Uniform Resource Names (URNs) are
   intended to serve as persistent, location-independent, resource
   identifiers".  The "info" URI scheme, on the other hand, does not
   assert the persistence of the identifiers created under this scheme
   but rather of the public namespaces grandfathered under this scheme.
   It exists primarily to disclose the identity of information assets
   and to facilitate a lightweight registration mechanism for public
   namespaces of identifiers managed according to the policies and
   business models of the Namespace Authorities.  The "info" URI scheme
   is neutral with respect to identifier persistence.  Moreover, for
   "info" to operate as a URN Network Identifier (NID) would require
   that "info" be constituted as a delegated naming authority.  It is
   not clear that a URN NID would be an appropriate choice for naming
   authority delegation.
]PRE]

[PRE[
   Further, the "info" URI scheme is not globally dereferenceable in
   contrast to the specific recommendation given in RFC 1737,
   "Functional Requirements for Uniform Resource Names" [RFC1737] that
   "It is strongly recommended that there be a mapping between the names
   generated by each naming authority and URLs".  Individual Namespace
   Authorities registered in the "info" Registry MAY, however, disclose
   references to service mechanisms and are encouraged to do so.
]PRE]

[PRE[
   An extra consideration is that the "urn" URI syntax explicitly
   excludes generic URI hierarchy by reserving the slash "/" character.
   An "info" URI, on the other hand, admits of hierarchical processing,
   while remaining neutral with respect to supporting actual hierarchy,
   and thus allows the slash "/" character (as well as more liberally
   allowing the ampersand "&" and tilde "~" characters).  It therefore
   represents a lower barrier to entry for Namespace Authorities in
   keeping with its intention of acting as a bridging mechanism to allow
   public namespaces to become part of the URI allocation.  In sum, an
   "info" URI is more widely supportive of "human transcribability" as
   discussed in RFC 3986 [RFC3986] than is a "urn" URI.
]PRE]

[PRE[
   Additionally, the "urn" URI syntax does not support "fragment"
   components as does the "info" URI syntax for indirect identification
   of secondary resources.
]PRE]


* 7.  Security Considerations

[PRE[
   The "info" URI scheme syntax is subject to the same security
   considerations as the generic URI syntax described in RFC 3986
   [RFC3986].
]PRE]

[PRE[
   While some "info" Namespace Authorities MAY choose to disclose
   service mechanisms, any security considerations resulting from the
   execution of such services fall outside the scope of this document.
   It is strongly recommended that the registration record of an "info"
   namespace include any such considerations.
]PRE]


* 8.  IANA Considerations

[PRE[
   The IANA registry for URI schemes
   <http://www.iana.org/assignments/uri-schemes.html> SHOULD be updated
   to include an entry for the "info" URI scheme when the "info" URI
   scheme is accepted for publication as an RFC.  This entry SHOULD
   contain the following values:
]PRE]

[PRE[
   Scheme Name: info
]PRE]

[PRE[
   Description: Information Assets with Identifiers in Public
                Namespaces
]PRE]

[PRE[
   Reference: RFC 4452
]PRE]


* 9.  Acknowledgements

[PRE[
   The authors acknowledge the contributions of Michael Mealling,
   Verisign, and Patrick Hochstenbach, Ghent University.
]PRE]


* 10.  References


** 10.1.  Normative References

[PRE[
   [RFC1737]  Sollins, K. and L. Masinter, "Functional Requirements for
              Uniform Resource Names", RFC 1737, December 1994.
]PRE]

[PRE[
   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.
]PRE]

[PRE[
   [RFC2141]  Moats, R., "URN Syntax", RFC 2141, May 1997.
]PRE]

[PRE[
   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.
]PRE]

[PRE[
   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.
]PRE]

[PRE[
   [RFC4234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 4234, October 2005.
]PRE]

[PRE[
   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", BCP 115, RFC
              4395, February 2006.
]PRE]

[PRE[
   [UNICODE]  The Unicode Consortium, "The Unicode Standard, Version
              4.0.0, defined by: The Unicode Standard, Version 4.0".
              (Reading, MA, Addison-Wesley, 2003).  ISBN 0-321-18578-1.
]PRE]


** 10.2.  Informative References

[PRE[
   [BIBCODE]  "NASA Astrophysics Data System Bibliographic Code",
              <http://adsdoc.harvard.edu/abs_doc/help_pages/data.html>.
]PRE]

[PRE[
   [DEWEY]    "Dewey Decimal Classification",
              <http://www.oclc.org/dewey/>.
]PRE]

[PRE[
   [LCCN]     "Library of Congress Control Number",
              <http://lcweb.loc.gov/marc/lccn_structure.html>.
]PRE]

[PRE[
   [NISO]     "National Information Standards Organization",
              <http://www.niso.org/>.
]PRE]

[PRE[
   [OCLCNUM]  "Online Computer Library Center OCLC Control Number",
              <http://www.oclc.org/bibformats/en/fixedfield/oclc.shtm>.
]PRE]

[PRE[
   [OFI]      "ANSI/NISO Z39.88-2004, "The OpenURL Framework for
              Context-Sensitive Services", ISBN 1-880124-61-0",
              <http://www.niso.org/standards/resources/Z39_88_2004.pdf>.
]PRE]

[PRE[
   [PMID]     "PubMed Overview", <http://www.ncbi.nlm.nih.gov/entrez/
              query/static/overview.html>.
]PRE]

[PRE[
   [SICI]     "ANSI/NISO Z39.56-1996 (R2002), "Serial Item and
              Contribution Identifier (SICI)", ISBN 1-880124-28-9",
              <http://www.niso.org/standards/resources/Z39-56.pdf>.
]PRE]


* Authors' Addresses

[PRE[
   Herbert Van de Sompel
   Los Alamos National Laboratory
   Research Library, MS-P362
   PO Box 1663
   Los Alamos, NM  87545-1362
   USA
]PRE]

[PRE[
   EMail: herbertv@lanl.gov
]PRE]

[PRE[
   Tony Hammond
   Nature Publishing Group
   Macmillan House
   4 Crinan Street
   London  N1 9XW
   UK
]PRE]

[PRE[
   EMail: t.hammond@nature.com
]PRE]

[PRE[
   Eamonn Neylon
   Manifest Solutions
   Bicester, Oxfordshire  OX26 2HX
   UK
]PRE]

[PRE[
   EMail: eneylon@manifestsolutions.com
]PRE]

[PRE[
   Stuart L. Weibel
   OCLC Online Computer Library Center, Inc.
   6565 Frantz Road
   Dublin, OH  43017-3395
   USA
]PRE]

[PRE[
   EMail: weibel@oclc.org
]PRE]

*Full Copyright Statement

[PRE[
   Copyright (C) The Internet Society (2006).
]PRE]

[PRE[
   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.
]PRE]

[PRE[
   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
]PRE]

*Intellectual Property

[PRE[
   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
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   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.
]PRE]

[PRE[
   Copies of IPR disclosures made to the IETF Secretariat and any
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   such proprietary rights by implementers or users of this
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   http://www.ietf.org/ipr.
]PRE]

[PRE[
   The IETF invites any interested party to bring to its attention any
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   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.
]PRE]

*Acknowledgement

[PRE[
   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).
]PRE]

* License

[[RFCのライセンス]]

* メモ