Applications Area WG (APPSAWG)                         S. Moonesamy, Ed.
Internet-Draft
Intended Status: Informational
Expires: December 9, 2012                                   June 7, 2012

                         The "about" URI Scheme
                 draft-ietf-appsawg-about-uri-scheme-07

Abstract

   This document describes the "about" URI scheme, which is widely used
   by web browsers and some other applications to designate access to
   their internal resources, such as settings, application information,
   hidden built-in functionality, and so on.

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Copyright and License Notice

   Copyright (c) 2012 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
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   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2. URI Scheme Specification  . . . . . . . . . . . . . . . . . . .  2
     2.1. URI Scheme Syntax . . . . . . . . . . . . . . . . . . . . .  2
     2.2. URI Scheme Semantics  . . . . . . . . . . . . . . . . . . .  2
       2.2.1. Well-known "about" URIs . . . . . . . . . . . . . . . .  3
     2.3. Encoding Considerations . . . . . . . . . . . . . . . . . .  3
   3. "about:blank" . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4. Security Considerations . . . . . . . . . . . . . . . . . . . .  3
   5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  4
     5.1. URI Scheme Registration . . . . . . . . . . . . . . . . . .  4
     5.2. A Registry for Well-known Tokens  . . . . . . . . . . . . .  4
       5.2.1. Registration procedure  . . . . . . . . . . . . . . . .  5
   6. References  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     6.1. Normative References  . . . . . . . . . . . . . . . . . . .  5
     6.2. Informative References  . . . . . . . . . . . . . . . . . .  6
   Appendix A.  Acknowledgments . . . . . . . . . . . . . . . . . . .  6
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  6

1. Introduction

   This document describes the "about" Uniform Resource Identifier (URI)
   scheme.  The "about" URI scheme is currently widely used by Web
   browsers to designate access to their internal resources such as
   settings, application information, so called "Easter eggs" (i.e.
   hidden feature or joke in an application).

2. URI Scheme Specification

2.1. URI Scheme Syntax

   The "about" URI syntactically conforms to the <about-uri> rule below,
   expressed using Augmented Backus-Naur Form (ABNF) [RFC5234]:

     about-uri = "about:" about-token [ about-query ] [ about-fragment ]
     about-token = *pchar
     about-query = "?" query
     about-fragment = "#" fragment
     pchar     = <as specified in RFC 3986, Appendix A>
     query     = <as specified in RFC 3986, Appendix A>
     fragment  = <as specified in RFC 3986, Appendix A>

2.2. URI Scheme Semantics




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     The resource which a particular "about" URI references is denoted
     by <about-token> part of the URI.  It is not a hierarchical element
     for a naming authority.  The <about-query> specifies additional
     information about its handling and/or the information that should
     be returned by the resource which the URI references.

     It is impossible to specify a binding between all the possible
     tokens and the semantics of "about" URIs that would contain such
     tokens.  Therefore the resource referenced by the URI is generally
     considered as specific to a Web browser implementation.

2.2.1. Well-known "about" URIs

     Some <about-token>s have been reserved as the behavior when the
     resource is referenced is well-known (Well-known tokens).

     A well-known "about" URI is a URI that has a well-known token as
     its <about-token> part.  It is recommended that such URIs be
     handled in accordance with the specification referenced in the
     Well-known Tokens registry (see Section 5.2).

     Well-known "about" URIs are intended to be registered when there is
     a need to codify the behavior of particular <about-token>.

2.3. Encoding Considerations

     "about" URIs are subject to encoding rules defined in RFC 3986
     [RFC3986].


3. "about:blank"

     This document defines one well-known token: "blank".  The
     "about:blank" URI refers to a resource represented in the browser
     by a blank page.


4. Security Considerations

     Security considerations for URIs are discussed in Section 7 of RFC
     3986 [RFC3986].  However, most of those provisions do not apply to
     the "about" URI scheme as they are mainly scoped to schemes used in
     the Internet.

     "about" URIs can sometimes refer to sensitive information, such as
     user passwords stored in a cache, or parameters that, if changed,
     could  affect user's data.  The application therefore needs to
     ensure that the user's data is secured and no threats are imposed



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     by "about" URIs.

5. IANA Considerations

5.1. URI Scheme Registration

     The registration of the "about" URI scheme in the "URI Schemes"
     registry is requested. The information below is provided according
     to the guidelines from RFC 4395 [RFC4395]:

     URI scheme name: about

     Status: Permanent

     URI scheme syntax: see Section 2.1 of RFC xxxx

     URI scheme semantics: see Section 2.2 of RFC xxxx

     URI scheme encoding considerations: see Section 2.3 of RFC xxxx

     Applications that use the scheme: "about" URIs are predominantly
     used by Web browsers.

     Security considerations: see Section 4 of RFC xxxx

     Contact: IETF Applications Area Directors <app-ads@tools.ietf.org>

     Author/Change controller: IESG <iesg@ietf.org> (on behalf of the
     IETF)

     References: see Section 5 of RFC xxxx

   [RFC Editor: Please replace xxxx with assigned RFC number]

5.2. A Registry for Well-known Tokens

   This document creates the '"about" URI Well-known Tokens' registry.

   The registry entries consist of three fields: Well-known Token,
   Description and Reference.  The Well-known Token field has to conform
   to <about-token> production defined in Section 2.1.  The initial set
   of assignments is as follows:

   +--------------+------------------------------------+-------------+
   | Well-known   | Description                        |  Reference  |
   | Token        |                                    |             |
   +------------------+--------------------------------+-------------+
   | blank        | The about:blank URI references a   | RFC xxxx    |



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   |              | blank page.                        |             |
   +--------------+------------------------------------+-------------+

5.2.1. Registration procedure

   The registration policy for this registry is "First Come First
   Served" as described in RFC 5226 [RFC5226].  The registrant of the
   token should provide the information mentioned in the following
   registration template:

   o Registered Token:  The desired Well-known token to be used in
     "about" URIs.

   o Intended usage:  A short description of how "about" URIs with the
     registered token is handled including information about the
     referenced resource.

   o Contact/Change controller:  Person (including contact information)
     authorized to change this registration.

   o Specification:  A stable reference to a document which specifies
     the registered "about" URI. The question of interoperability does
     not arise.  The key motivation is to have a reference to a
     specification documenting well-known behavior of the "about" URI in
     Web browsers.  As a rule of thumb if the behavior is common to two
     or more Web browser implementations it can be considered as well-
     known.  An existing assignment may be duplicated if the registered
     token is used in more than one Web browser implementation.

   The following is a template for the "blank" token:

   o Registered Token:  blank
   o Intended usage:  The about:blank URI references a blank page.
   o Contact/Change controller:  IESG <iesg@ietf.org> (on behalf of
     IETF).
   o Specification:  RFC xxxx. [RFC Editor: Please replace xxxx with
     assigned RFC number]

6. References

6.1. Normative References

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

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



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              May 2008.

   [RFC5234]  Crocker, D., Ed., and P. Overell, "Augmented BNF for
              Syntax Specifications: ABNF", STD 68, RFC 5234, January
              2008.

6.2. Informative References

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

Appendix A.  Acknowledgments

   This document has been formed from the draft initially authored by
   Lachlan Hunt and Joseph Holsten.  Additionally, the contributions of
   Frank Ellermann and Alexey Melnikov are gratefully acknowledged.
   Barry Leiba and Murray Kucherawy deserve a special credit for
   providing a great amount of text which has been used in this
   document.

   Lachlan Hunt and Mykyta Yevstifeyev edited previous versions of this
   document.  Tim Bray and John Klensin provided suggestions about how
   to improve the document.

Authors' Addresses


   S. Moonesamy (editor)
   76, Ylang Ylang Avenue
   Quatre Bornes
   Mauritius

   EMail: sm+ietf@elandsys.com

















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