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Versions: (draft-hansen-iri-4395bis-irireg) 00 01 02 03 04 draft-thaler-appsawg-uri-scheme-reg

Network Working Group                                          T. Hansen
Internet-Draft                                         AT&T Laboratories
Obsoletes: 4395 (if approved)                                  T. Hardie
Intended status: BCP                     Panasonic Wireless Research Lab
Expires: June 16, 2012                                       L. Masinter
                                                                   Adobe
                                                       December 14, 2011


     Guidelines and Registration Procedures for New URI/IRI Schemes
                    draft-ietf-iri-4395bis-irireg-04

Abstract

   This document updates the guidelines and recommendations for the
   definition of Uniform Resource Identifier (URI) schemes, and extends
   the registry and guidelines to apply when the schemes are used with
   Internationalized Resource Identifiers (IRIs).  It also updates the
   process and IANA registry for URI/IRI schemes.  It obsoletes RFC
   4395.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 16, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conformance Guidelines . . . . . . . . . . . . . . . . . . . .  4
   3.  Guidelines for Permanent URI/IRI Scheme Definitions  . . . . .  4
     3.1.  Demonstratable, New, Long-Lived Utility  . . . . . . . . .  4
     3.2.  Syntactic Compatibility  . . . . . . . . . . . . . . . . .  5
     3.3.  Well-Defined . . . . . . . . . . . . . . . . . . . . . . .  5
     3.4.  Definition of Operations . . . . . . . . . . . . . . . . .  6
     3.5.  Context of Use . . . . . . . . . . . . . . . . . . . . . .  7
     3.6.  Internationalization and Character Encoding  . . . . . . .  7
     3.7.  Clear Security Considerations  . . . . . . . . . . . . . .  7
     3.8.  Scheme Name Considerations . . . . . . . . . . . . . . . .  8
   4.  Guidelines for Provisional URI/IRI Scheme Registration . . . .  8
   5.  Guidelines for Historical URI/IRI Scheme Registration  . . . .  9
   6.  URI/IRI Scheme Registration Procedure  . . . . . . . . . . . .  9
     6.1.  General  . . . . . . . . . . . . . . . . . . . . . . . . .  9
     6.2.  Registration Procedures  . . . . . . . . . . . . . . . . . 10
     6.3.  Change Control . . . . . . . . . . . . . . . . . . . . . . 11
     6.4.  URI/IRI Scheme Registration Template . . . . . . . . . . . 11
   7.  The "example" Scheme . . . . . . . . . . . . . . . . . . . . . 12
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   Appendix A.  Changes Since RFC 4395  . . . . . . . . . . . . . . . 14
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 14
     11.2. Informative References . . . . . . . . . . . . . . . . . . 15
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
















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1.  Introduction

   The Uniform Resource Identifier (URI) protocol element and generic
   syntax is defined by [RFC3986].  Each URI begins with a scheme name,
   as defined by Section 3.1 of RFC 3986, that refers to a specification
   for identifiers within that scheme.  The URI syntax provides a
   federated and extensible naming system, where each scheme's
   specification may further restrict the syntax and define the
   semantics of identifiers using that scheme.  As originally defined,
   URIs only allowed a limited repertoire of characters chosen from US-
   ASCII.

   An Interationalized Resource Identifier (IRI), as defined by
   [RFC3987bis], extends the URI syntax to allow characters from a much
   greater repertoire, to accomodate resource identifiers from the
   world's languages.  The same schemes used in URIs are used in IRIs.
   The term Resource Identifier (RI) is used as a shorthand for both
   URIs and IRIs.  [RFC3987] introduced IRIs by defining a mapping
   between URIs and IRIs; [RFC3987bis] updates that definition, allowing
   an IRI to be interpreted directly without translating into a URI.

   This document obsoletes [RFC4395], which in turn obsoleted [RFC2717]
   and [RFC2718].  Recent documents have used the terms "URI"/"IRI" for
   all resource identifiers, avoiding the term "URL" and reserving the
   term "URN" explicitly for those URIs/IRIs using the "urn" scheme name
   ([RFC2141]).  URN "namespaces" ([RFC3406]) are specific to the "urn"
   scheme and are not covered explicitly by this specification.

   This document extends the URI scheme registry to be a registry of
   URI/IRI schemes (i.e., applicable to both URIs and IRIs).  This
   document also provides updated guidelines for the definition of new
   schemes, for consideration by those who are defining, registering, or
   evaluating those definitions, as well as a process and mechanism for
   registering URI/IRI schemes within the IANA URI scheme registry.
   There is a single namespace for registered schemes.  Within that
   namespace, there are values that are approved as meeting a set of
   criteria for permanent URI/IRI schemes.  Other scheme names may also
   be registered provisionally or historically, without necessarily
   meeting those criteria.  The intent of the registry is to:

   o  provide a central point of discovery for established URI/IRI
      scheme names, and easy location of their defining documents;
   o  discourage use of the same scheme name for different purposes;
   o  help those proposing new scheme names to discern established
      trends and conventions, and avoid names that might be confused
      with existing ones;





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   o  encourage registration by setting a low barrier for provisional
      registrations.

   There is no separate, independent registry or registration process
   for IRIs: the URI Scheme Registry is to be used for both URIs and
   IRIs.  Previously, those who wish to describe resource identifiers
   that are useful as IRIs were encouraged to define the corresponding
   URI syntax, and note that the IRI usage follows the rules and
   transformations defined in [RFC3987].  This document changes that
   advice to encourage explicit definition of the scheme and allowable
   syntax elements within the larger character repertoire of IRIs, as
   defined by [RFC3987bis].

   A scheme definition cannot override the overall syntax for IRIs.  For
   example, this means that fragment identifiers (#) cannot be re-used
   outside the generic syntax restrictions, and in particular scheme-
   specific syntax cannot override the fragment identifier syntax
   because it is generic.


2.  Conformance Guidelines

   Within this document, the key words MUST, MAY, SHOULD, REQUIRED,
   RECOMMENDED, and so forth are used within the general meanings
   established in [RFC2119], within the context that they are
   requirements on future registration specifications.


3.  Guidelines for Permanent URI/IRI Scheme Definitions

   This section gives considerations for new URI/IRI schemes.  Meeting
   these guidelines is REQUIRED for permanent scheme registration.
   Meeting these guidelines is also RECOMMENDED for provisional
   registration, as described in Section 4.

3.1.  Demonstratable, New, Long-Lived Utility

   The use and deployment of new URI/IRI schemes in the Internet
   infrastructure may be costly; some parts of URI/IRI processing may be
   scheme-dependent, and deployed software already processes URIs and
   IRIs of well-known schemes.  Introducing a new scheme may require
   additional software, not only for client software and user agents but
   also in additional parts of the network infrastructure (gateways,
   proxies, caches) [W3CWebArch].  URI/IRI schemes constitute a single,
   global namespace; it is desirable to avoid contention over use of
   short, mnemonic scheme names.  For these reasons, the unbounded
   registration of new schemes is harmful.  New schemes should have
   utility to the Internet community beyond that available with already



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   registered schemes.  The registration document SHOULD discuss the
   utility of the scheme being registered.

3.2.  Syntactic Compatibility

   [RFC3986] defines the generic syntax for all URI schemes, along with
   the syntax of common URI components that are used by many URI schemes
   to define hierarchical identifiers.  [RFC3987] and subsequently
   [RFC3987bis] extended this generic syntax to cover IRIs.  All URI/IRI
   scheme specifications MUST define their own syntax such that all
   strings matching their scheme-specific syntax will also match the
   <absolute-URI> grammar described in [RFC3987bis].

   New schemes SHOULD reuse the common components of [RFC3987bis] for
   the definition of hierarchical naming schemes.  However, if there is
   a strong reason for a scheme not to use the hierarchical syntax, then
   the new scheme definition SHOULD follow the syntax of previously
   registered schemes.

   Schemes that are not intended for use with relative URIs/IRIs SHOULD
   avoid use of the forward slash "/" character, which is used for
   hierarchical delimiters, and the complete path segments "." and ".."
   (dot-segments).

   Avoid improper use of "//".  The use of double slashes in the first
   part of a URI/IRI is not an artistic indicator that what follows is a
   URI/IRI: Double slashes are used ONLY when the syntax of the <scheme-
   specific-part> contains a hierarchical structure.  In URIs and IRIs
   from such schemes, the use of double slashes indicates that what
   follows is the top hierarchical element for a naming authority.
   (Section 3.2 of RFC 3986 has more details.)  Schemes that do not
   contain a conformant hierarchical structure in their <scheme-
   specific-part> SHOULD NOT use double slashes following the
   "<scheme>:" string.

   New schemes SHOULD clearly define the role of [RFC3986] reserved
   characters in URIs/IRIs of the scheme being defined.  The syntax of
   the new scheme should be clear about which of the "reserved" set of
   characters are used as delimiters within the URIs/IRIs of the new
   scheme, and when those characters must be escaped, versus when they
   may be used without escaping.

3.3.  Well-Defined

   While URIs/IRIs may or may not be defined as locators in practice, a
   scheme definition itself MUST be clear as to how it is expected to
   function.  Schemes that are not intended to be used as locators
   SHOULD describe how the resource identified can be determined or



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   accessed by software that obtains a URI/IRI of that scheme.

   For schemes that function as locators, it is important that the
   mechanism of resource location be clearly defined.  This might mean
   different things depending on the nature of the scheme.

   In many cases, new schemes are defined as ways to translate between
   other namespaces or protocols and the general framework of URIs.  For
   example, the "ftp" scheme translates into the FTP protocol, while the
   "mid" scheme translates into a Message-ID identifier of an email
   message.  For such schemes, the description of the mapping must be
   complete, and in sufficient detail so that the mapping in both
   directions is clear: how to map from a URI/IRI into an identifier or
   set of protocol actions or name in the target namespace, and how
   legal values in the base namespace, or legal protocol interactions,
   might be represented in a valid URI or IRI.  In particular, the
   mapping should describe the mechanisms for encoding binary or
   character strings within valid character sequences in a URI/IRI (See
   Section 3.6 for guidelines).  If not all legal values or protocol
   interactions of the base standard can be represented using the
   scheme, the definition should be clear about which subset are
   allowed, and why.

3.4.  Definition of Operations

   As part of the definition of how a URI/IRI identifies a resource, a
   scheme definition SHOULD define the applicable set of operations that
   may be performed on a resource using the RI as its identifier.  A
   model for this is HTTP; an HTTP resource can be operated on by GET,
   POST, PUT, and a number of other operations available through the
   HTTP protocol.  The scheme definition should describe all well-
   defined operations on the resource identifier, and what they are
   supposed to do.

   Some schemes don't fit into the "information access" paradigm of
   URIs/IRIs.  For example, "telnet" provides location information for
   initiating a bi-directional data stream to a remote host; the only
   operation defined is to initiate the connection.  In any case, the
   operations appropriate for a scheme should be documented.

   Note: It is perfectly valid to say that "no operation apart from GET
   is defined for this RI".  It is also valid to say that "there's only
   one operation defined for this RI, and it's not very GET-like".  The
   important point is that what is defined on this scheme is described.







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3.5.  Context of Use

   In general, URIs/IRIs are used within a broad range of protocols and
   applications.  Most commonly, URIs/IRIs are used as references to
   resources within directories or hypertext documents, as hyperlinks to
   other resources.  In some cases, a scheme is intended for use within
   a different, specific set of protocols or applications.  If so, the
   scheme definition SHOULD describe the intended use and include
   references to documentation that define the applications and/or
   protocols cited.

3.6.  Internationalization and Character Encoding

   When describing schemes in which (some of) the elements of the URI or
   IRI are actually representations of human-readable text, care should
   be taken not to introduce unnecessary variety in the ways in which
   characters are encoded into octets and then into characters; see
   [RFC3987bis] and Section 2.5 of [RFC3986] for guidelines.  If URIs/
   IRIs of a scheme contain any text fields, the scheme definition MUST
   describe the ways in which characters are encoded and any
   compatibility issues with IRIs of the scheme.

   Specifications for IRIs schemes MUST be described in terms of
   processing an IRI as a sequence of Unicode codepoints, without
   reference to the encoding of those code points as a sequence of
   bytes, using UTF-8 or UTF-16.  The scheme specification SHOULD be as
   restrictive as possible regarding what characters are allowed in the
   URI/IRI, because some characters can create several different
   security considerations (see for example [RFC4690]).

   All percent-encoded variants are automatically included by definition
   for any character given in an IRI production.  This means that if you
   want to restrict the URI percent-encoded forms in some way, you must
   restrict the Unicode forms that would lead to them.

3.7.  Clear Security Considerations

   Definitions of schemes MUST be accompanied by a clear analysis of the
   security implications for systems that use the scheme; this follows
   the practice of Security Consideration sections within IANA
   registrations [RFC5226].

   In particular, Section 7 of RFC 3986 [RFC3986] describes general
   security considerations for URIs, while [RFC3987bis] gives those for
   IRIs.  The definition of an individual URI/IRI scheme should note
   which of these apply to the specified scheme.





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3.8.  Scheme Name Considerations

   Section 3.1 of RFC 3986 defines the syntax of a URI scheme name; this
   sytax remains the same for IRIs.  New registered schemes
   registrations MUST follow this syntax, which only allows a limited
   repertoire of characters (taken from US-ASCII).  Although the syntax
   for the scheme name in URI/IRIs is case insensitive, the scheme names
   itself MUST be registered using lowercase letters.

   URI/IRI scheme names should be short, but also sufficiently
   descriptive and distinguished to avoid problems.

   Avoid names or other symbols that might cause problems with rights to
   use the name in IETF specifications and Internet protocols.  For
   example, be careful with trademark and service mark names.  (See
   Section 7.4 of [RFC3978].)

   Avoid using names that are either very general purpose or associated
   in the community with some other application or protocol.  Avoid
   scheme names that are overly general or grandiose in scope (e.g.,
   that allude to their "universal" or "standard" nature.)

   Organizations that desire a private name space for URI scheme names
   are encouraged to use a prefix based on their domain name, expressed
   in reverse order.  For example, a URI scheme name of com-example-info
   might be registered by the vendor that owns the example.com domain
   name.


4.  Guidelines for Provisional URI/IRI Scheme Registration

   Provisional registration can be an intermediate step on the way to
   permanent registration, e.g., before the scheme specification is
   finalized.  Provisional registration is also appropriate for schemes
   that are known to be used, but where a definitive specification is
   not available.  There is no time limit for provisional registration.

   While the guidelines in Section 3 are REQUIRED for permanent
   registration, they are RECOMMENDED for provisional registration.  For
   a provisional registration, the following are REQUIRED:

   o  The scheme name meets the syntactic requirements of Section 3.8
      and the encoding requirements of Section 3.6.
   o  There is not already an entry with the same scheme name.  (In the
      unfortunate case that there are multiple, different uses of the
      same scheme name, the IESG may approve a request to modify an
      existing entry to note the separate use.)




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   o  Contact information identifying the person supplying the
      registration is included.  Previously unregistered schemes
      discovered in use may be registered by third parties (even if not
      on behalf of those who created the scheme).  In this case, both
      the registering party and the scheme creator SHOULD be identified.
   o  If no permanent, citable specification for the scheme definition
      is included, credible reasons for not providing it should be
      given.
   o  The scheme definition SHOULD include a clear Security
      Considerations (Section 3.7) or explain why a full security
      analysis is not available (e.g., in a third-party scheme
      registration).
   o  If the scheme definition does not meet the guidelines laid out in
      Section 3, the differences and reasons SHOULD be noted.


5.  Guidelines for Historical URI/IRI Scheme Registration

   In some circumstances, it is appropriate to note a URI scheme that
   was once in use or registered but for whatever reason is no longer in
   common use or the use is not recommended.  In this case, it is
   possible for an individual to request that the scheme be registered
   (newly, or as an update to an existing registration) as 'historical'.
   Any scheme that is no longer in common use MAY be designated as
   historical; the registration should contain some indication to where
   the scheme was previously defined or documented.


6.  URI/IRI Scheme Registration Procedure

6.1.  General

   The URI/IRI registration process is described in the terminology of
   [RFC5226].  The registration process is an optional mailing list
   review, followed by "Expert Review".  The registration request should
   note the desired status.  The Designated Expert will evaluate the
   request against the criteria of the requested status.  In the case of
   a permanent registration request, the Designated Expert may:
   o  Accept the specification of the scheme for permanent registration.
   o  Suggest provisional registration instead.
   o  Request IETF review and IESG approval; in the meanwhile, suggest
      provisional registration.

   URI/IRI scheme definitions contained within other IETF documents
   (Informational, Experimental, or Standards-Track RFCs) must also
   undergo Expert Review; in the case of Standards-Track documents,
   permanent registration status approval is required.




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   The registration procedure for URI schemes is intended to be very
   lightweight for non-contentious registrations.  For the most part, we
   expect the good sense of submitters and reviewers, guided by these
   procedures, to achieve an acceptable and useful consensus for the
   community.

   In exceptional cases, where the negotiating parties cannot form a
   consensus, the final arbiter of any contested registration shall be
   the IESG.

   If parties achieve consensus on a registration proposal that does not
   fully conform to the strict wording of this procedure, this should be
   drawn to the attention of a relevant member of the IESG.

6.2.  Registration Procedures

   Someone wishing to register a new URI/IRI scheme MUST:
   1.  Check the IANA URI scheme registry to see whether or not there is
       already an entry for the desired name.  If there is already an
       entry under the name, choose a different URI scheme name, or
       update the existing scheme definition.
   2.  Prepare a URI/IRI scheme registration template, as specified in
       Section 6.4.  The scheme registration template may be contained
       in an Internet Draft, submitted alone, or as part of some other
       permanently available, stable, protocol specification.  The
       template may also be submitted in some other form (as part of
       another document or as a stand-alone document), but the contents
       will be treated as an "IETF Contribution" under the guidelines of
       [RFC3978].
   3.  Send a copy of the template or a pointer to the containing
       document (with specific reference to the section with the
       template) to the mailing list uri-review@ietf.org, requesting
       review.  In addition, request review on other relevant mailing
       lists as appropriate.  For example, general discussion of URI/IRI
       syntactical issues could be discussed on uri@w3.org; schemes for
       a network protocol could be discussed on a mailing list for that
       protocol.  Allow a reasonable time for discussion and comments.
       Four weeks is reasonable for a permanent registration requests.
   4.  Respond to review comments and make revisions to the proposed
       registration as needed to bring it into line with the guidelines
       given in this document.
   5.  Submit the (possibly updated) registration template (or pointer
       to document containing it) to IANA at iana@iana.org, specifying
       whether 'permanent' or 'provisional' registration is requested.

   Upon receipt of a URI/IRI scheme registration request, the following
   steps MUST be followed:




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   1.  IANA checks the submission for completeness; if sections are
       missing or citations are not correct, IANA may reject the
       registration request.
   2.  IANA checks the current registry for a entry with the same name;
       if such a registry exists, IANA may reject the registration
       request.
   3.  IANA requests Expert Review of the registration request against
       the corresponding guidelines (from this document.)
   4.  The Designated Expert may request additional review or
       discussion, as necessary.
   5.  If Expert Review recommends registration 'provisional' or
       'permanent' registration, IANA adds the registration to the
       appropriate registry.
   6.  Unless Expert Review has explicitly rejected the registration
       request within two weeks, IANA should automatically add the
       registration in the 'provisional' registry.

   Either based on an explicit request or independently initiated, the
   Designated Expert or IESG may request the upgrade of a 'provisional'
   registration to a 'permanent' one.  In such cases, IANA should move
   the corresponding entry from the provisional registry.

6.3.  Change Control

   Registrations may be updated in each registry by the same mechanism
   as required for an initial registration.  In cases where the original
   definition of the scheme is contained in an IESG-approved document,
   update of the specification also requires IESG approval.

   Provisional registrations may be updated by the original registrant
   or anyone designated by the original registrant.  In addition, the
   IESG may reassign responsibility for a provisional registration
   scheme, or may request specific changes to a scheme registration.
   This will enable changes to be made to schemes where the original
   registrant is out of contact, or unwilling or unable to make changes.

   Transition from 'provisional' to 'permanent' status may be requested
   and approved in the same manner as a new 'permanent' registration.
   Transition from 'permanent' to 'historical' status requires IESG
   approval.  Transition from 'provisional' to 'historical' may be
   requested by anyone authorized to update the provisional
   registration.

6.4.  URI/IRI Scheme Registration Template

   This template describes the fields that must be supplied in a URI/IRI
   scheme registration request:




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   Resource Identifier (RI) Scheme name:
      See Section 3.8 for guidelines.
   Status:
      This reflects the status requested, and should be one of
      'permanent', 'provisional', or 'historical'.
   Scheme syntax:
      See Section 3.2 for guidelines.
   Scheme semantics:
      See Section 3.3 and Section 3.4 for guidelines.
   Encoding considerations:
      See Section 3.3 and Section 3.6 for guidelines.
   Applications/protocols that use this scheme name:
      See Section 3.5.
   Interoperability considerations:
      If the person or group registering the scheme is aware of any
      details regarding the scheme that might impact interoperability,
      identify them here.  For example: proprietary or uncommon encoding
      methods; inability to support multibyte character sets;
      incompatibility with types or versions of any underlying protocol.
   Security considerations:
      See Section 3.7 for guidelines.
   Contact:
      Person (including contact information) to contact for further
      information.
   Author/Change controller:
      Person (including contact information) authorized to change this.
   References:
      Include full citations for all referenced documents.  Registration
      templates for provisional registration may be included in an
      Internet Draft; when the documents expire or are approved for
      publication as an RFC, the registration will be updated.


7.  The "example" Scheme

   There is a need for a URI/IRI Scheme name that can be used for
   examples in documentation without fear of conflicts with current or
   future actual schemes.  The URI/IRI Scheme "example" is hereby
   registered as a Permanent URI/IRI Scheme for that purpose.
   Scheme name:  example
   Status:  permanent
   Scheme syntax:  The entire range of allowable syntax for URI/IRI
      schemes specified in [RFC3987bis] is allowed for "example" URI/
      IRIs.







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   Scheme semantics:  URI/IRIs in the "example" scheme should be used
      for documentation purposes only.  The use of "example" URIs/IRIs
      must not be used as locators, identify any resources, or specify
      any particular set of operations.
   Encoding considerations:  See Section 2.5 of [RFC3986] for
      guidelines.
   Applications/protocols that use this URI scheme name:  The "example"
      URI should be used for documentation purposes only.  It MUST not
      be used for any protocol.
   Interoperability considerations:  None.
   Security considerations:  None.
   Contact:  N/A
   Author/Change controller:  IETF
   References:  This RFC XXXX.
      RFC Editor Note: Replace XXXX with this RFC's reference.


8.  IANA Considerations

   Previously, the former "URL Scheme" registry was replaced by the
   Uniform Resource Identifier scheme registry.  The process was based
   on [RFC5226] "Expert Review" with an initial (optional) mailing list
   review.

   The updated template has an additional field for the status of the
   scheme, and the procedures for entering new name schemes have been
   augmented.  Section 6 establishes the process for new URI/IRI scheme
   registration.

   IANA is requested to update the name of the registry "URI Schemes" to
   "URI/IRI Schemes".  The registry should be updated to point to this
   document.  For the tables within that registry "Permanent URI
   Schemes" should become "Permanent URI/IRI Schemes", "Provisional URI
   Schemes" should become "Provisional URI/IRI Schemes", and "Historical
   URI Schemes" should become "Historical URI/IRI Schemes".

   The example URI scheme "example" is hereby registered.  (See the
   template above for registration.)


9.  Security Considerations

   All registered values are expected to contain accurate security
   consideration sections; 'permanent' registered scheme names are
   expected to contain complete definitions.

   Information concerning possible security vulnerabilities of a
   protocol may change over time.  Consequently, claims as to the



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   security properties of a registered URI/IRI scheme may change as
   well.  As new vulnerabilities are discovered, information about such
   vulnerabilities may need to be attached to existing documentation, so
   that users are not misled as to the true security properties of a
   registered URI scheme.


10.  Acknowledgements

   Many thanks to Patrick Faltstrom for his comments on this version.

   Many thanks to Paul Hoffmann, Ira McDonald, Roy Fielding, Stu Weibel,
   Tony Hammond, Charles Lindsey, Mark Baker, and other members of the
   uri@w3.org mailing list for their comments on earlier versions.

   Parts of this document are based on [RFC2717], [RFC2718] and
   [RFC3864].  Some of the ideas about use of URIs were taken from the
   "Architecture of the World Wide Web" [W3CWebArch].


Appendix A.  Changes Since RFC 4395

   1.  Significant edits to be clear that a "URI scheme" and an "IRI
       scheme" are the same thing.
   2.  Added the "example:" URL Scheme.
   3.  Allow for IRI-specific scheme registration.
   4.  Clarify that the URI scheme registry is also the IRI scheme
       registry.


11.  References

11.1.  Normative References

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

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

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC3978]  Bradner, S., "IETF Rights in Contributions", RFC 3978,
              March 2005.

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



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              RFC 3986, January 2005.

   [RFC3987bis]
              Duerst, M., Masinter, L., and M. Suignard,
              "Internationalized Resource Identifiers (IRIs)",
              September 2010,
              <http://tools.ietf.org/id/draft-ietf-iri-3987bis>.

11.2.  Informative References

   [RFC2717]  Petke, R. and I. King, "Registration Procedures for URL
              Scheme Names", BCP 35, RFC 2717, November 1999.

   [RFC2718]  Masinter, L., Alvestrand, H., Zigmond, D., and R. Petke,
              "Guidelines for new URL Schemes", RFC 2718, November 1999.

   [RFC3406]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
              "Uniform Resource Names (URN) Namespace Definition
              Mechanisms", BCP 66, RFC 3406, October 2002.

   [RFC3864]  Klyne, G., Nottingham, M., and J. Mogul, "Registration
              Procedures for Message Header Fields", BCP 90, RFC 3864,
              September 2004.

   [RFC3987]  Duerst, M. and M. Suignard, "Internationalized Resource
              Identifiers (IRIs)", RFC 3987, January 2005.

   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", BCP 35,
              RFC 4395, February 2006.

   [RFC4690]  Klensin, J., Faltstrom, P., Karp, C., and IAB, "Review and
              Recommendations for Internationalized Domain Names
              (IDNs)", RFC 4690, September 2006.

   [W3CWebArch]
              W3C Technical Architecture Group, "Architecture of the
              World Wide Web, Volume One", December 2004,
              <http://www.w3.org/TR/webarch/>.












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Authors' Addresses

   Tony Hansen
   AT&T Laboratories
   200 Laurel Ave.
   Middletown, NJ  07748
   USA

   Email: tony+urireg@maillennium.att.com


   Ted Hardie
   Panasonic Wireless Research Lab
   10900 Tantau Ave.
   Cupertino, CA
   USA

   Phone: +1 408 628 5864
   Email: ted.ietf@gmail.com


   Larry Masinter
   Adobe
   345 Park Ave.
   San Jose, CA  95110
   US

   Phone: +1 408 536 3024
   Email: masinter@adobe.com
   URI:   http://larry.masinter.net





















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