The "about" URI Scheme
RFC 6694

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Internet Engineering Task Force (IETF)                 S. Moonesamy, Ed.
Request for Comments: 6694                                   August 2012
Category: Informational
ISSN: 2070-1721

                         The "about" URI Scheme

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.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6694.

Copyright 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
   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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   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.

Moonesamy                     Informational                     [Page 1]
RFC 6694                 The "about" URI Scheme              August 2012

Table of Contents

   1. Introduction ....................................................2
   2. URI Scheme Specification ........................................2
      2.1. URI Scheme Syntax ..........................................2
      2.2. URI Scheme Semantics .......................................3
           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 ...........................5
           5.2.1. Registration Procedure ..............................5
   6. References ......................................................6
      6.1. Normative References .......................................6
      6.2. Informative References .....................................6
   Appendix A. Acknowledgments ........................................7

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, and so-called "Easter eggs" (i.e.,
   a 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 the 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>

Moonesamy                     Informational                     [Page 2]
RFC 6694                 The "about" URI Scheme              August 2012

2.2.  URI Scheme Semantics

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

   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
   to be specific to a Web browser implementation.

2.2.1.  Well-Known "about" URIs

   Some <about-token>s have been reserved, as the behavior of the