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Network Working Group                                            I. King
Internet-Draft                                     Microsoft Corporation
Expires: March 6, 2004                                       L. Masinter
                                              Adobe Systems Incorporated
                                                       September 6, 2003

               The vnd and prs Trees for URI Scheme Names

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
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   This Internet-Draft will expire on March 6, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.


   This document describes a way in which individuals and vendors can
   define URI schemes in a way that avoids name collisions, but with
   relaxed registration requirements. This is done by allowing URI
   schemes that start with "vnd-" or "prs-", analogous to similar
   mechanism MIME media types.


   Discuss this document on uri@w3.org. A HTML version of this document
   can be found at http://larry.masinter.net/vnduri.html.

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1. Introduction

   The registration process for URI schemes, described in RFC 2717 [2],
   requires IESG review and approval of all proposed scheme names within
   the "IETF tree", which encompasses simple, short, often descriptive
   URI scheme names (such as http:, fax:, or mailto:).

   However, there are circumstances where it is desirable to allocate a
   URI scheme name outside of this process. This document establishes
   alternative trees, "vnd-" and "prs-", corresponding to the similar
   concept for MIME type registrations[4].  The rules for use and
   registration of URI schemes with in these trees are intended to be
   analogous those for the corresponding MIME type trees.

   The "vnd-" tree is used for URI schemes associated with available
   products or services; "vendor" or "producer" are construed as
   equivalent and broadly. The registration belongs to the vendor or
   organization producing software or offering a service that utilizes
   the URI scheme. Registration in the vendor tree is distinguished by
   the leading "vnd-", followed, at the discretion of the registration,
   either by the scheme name or (preferably) by an IANA-approved
   designation of the producer's name, followed by the specific scheme
   name. Designations of producers should match those used for media
   types, and follows the same criteria.

   Similarly, the "prs-" tree is intended for URI schemes used
   experimentally or as individual contributions.  The owner of
   "personal" registrations and associated specifications is the person
   or entity making the registration, or one to whom responsibility has
   been transferred as described below.

   Note that earlier drafts of this document suggested using "." as the
   delimiter between "vnd" and the URI scheme. However, RFC 2717 [2]
   reserved the "-" character for non-IETF registrations (and not "."),
   so the delimiter was changed for compatibility.  Because these
   earlier drafts were available for several years, however, there may
   be some URI schemes with "vnd." still in use.

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2. Syntax

   The general syntax for these new trees follows the syntax recommended
   in RFC 2717 [2]:

        scheme     = ("vnd-" / "prs-") [ vendor-id "-" ] scheme-id
        vendor-id  = ALPHA *(ALPHA / DIGIT / "+" )
        scheme-id  = ALPHA *(ALPHA / DIGIT / "+" / "-" / "." )

2.1 Syntax notes

   Note that RFC 2396 [1] limits the characters in URI scheme names to
   include only letters, digits, plus ("+"), period ("."), or hyphen
   ("-"); further, that although scheme names are case insensitive, the
   canonical form is lowercase and documents that specify schemes must
   do so using lowercase letters. These restrictions apply to
   <vendor-id> and <scheme-id>.

   To avoid confusion, a <vendor-id> may not contain a hyphen "-" or a
   period ".".

2.2 Choosing a vendor-id

   The vendor-id is an IANA-approved designation, consisting of a short
   string of characters that is sufficient to uniquely identify the

   To avoid exhaustion of the namespace, vendors are encouraged to
   establish only one vendor-id, although it is recognized that large
   organizations may actually consist of multiple sub-units.
   Organizations should use the same vendor-id for MIME types and URI

   The organization may be a business (whether for-profit or not),
   governmental unit, educational institution, or any other entity,
   organization or community which is regularly engaged in producing
   software.  The term "vendor" is used in this document for simplicity.

   IANA may choose to reject a request for a particular vendor-id or
   propose a different vendor-id based on IANA's best judgment as to
   whether the string proposed is appropriate for the organization
   requesting it.

2.3 Syntax for scheme-id

   There are no formal restrictions on the scheme-id except that the
   characters be chosen from those allowed in a URI scheme name

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   (letters, digits, plus, period, hyphen), and be registered using the
   lowercase form.  The registrar is encouraged to select a scheme-id
   that is short and descriptive of its purpose.

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3. Requirements for Scheme Name Registration

3.1 General Requirements

   The purpose of registration is to give notice to the Internet
   community of the existence the scheme.  Registration of the vendor-id
   is required, and serves to partition the namespace (and avoid

   Similarly, to avoid collision and misuse, registration of "prs-" and
   "vnd-" schemes without vendor-id parts is required.

   If the vendor-id is registered, registration of a specific scheme-id
   is optional; if supplied, the registrar may supply whatever
   information is appropriate. Registration may only consist of the
   scheme name, or might include a pointer to appropriate documentation
   of the scheme's syntax and semantics.

3.2 Registering the vendor-id

   The request for vendor-id registration may be sent separately, or may
   be included in a scheme name registration.  The initial request for
   vendor-id names must contain the proposed vendor-id, the vendor's
   legal business name, principal business address, telephone number,
   and contact information for a person or position that will be
   responsible for the use of the vendor's subtree.  The vendor should
   inform IANA if of changes in this information, and may explicitly
   transfer ownership of its vendor-id and associated subtree.

   A given vendor-id can be issued only once, and it does not expire.
   This is to avoid possible name collisions, since using a registered
   vendor-id means there may be URI schemes that are not otherwise

   IANA should maintain a public registry of the vendor-id's, together
   with contact information for each vendor so registered.  A form for
   submission of this information (together with scheme information as
   appropriate) is provided in this document.

3.3 Publishing Scheme-Specific Information

   While public exposure and review of a URI scheme created in the
   "vnd-" or "prs-" tree is not required, it is encouraged.  The
   'uri-review@ietf.org' mailing list may be used for review of new URI
   schemes, even if they are not in the IETF tree.

   Publication of the scheme description as an Informational RFC may be
   appropriate for those schemes of sufficient interest to the IETF

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   community; however, this mechanism is usually appropriate only for
   URI schemes in the IETF tree.

   Note that a separate, explicit request should be made to IANA (at
   IANA@iana.org) to register schemes; discussion on uri-review@ietf.org
   is insufficient. The request should follow the form is provided in
   Appendix A of this document.

   Internet Drafts intended for publication as Informational RFCs
   describing new URI schemes should also contain an 'IANA
   Considerations' section with the request for registration included.
   The registration would occur at the time of publication of the
   document as an RFC.

3.4 Change Control

   The vendor is the owner of all schemes within its registered tree,
   has sole responsibility for management of the sub-tree created by its
   vendor-id, and owns change control for any URI schemes deployed
   therein.  If a vendor publishes information about a vnd URI scheme by
   either of the methods described above, changes to the syntax or
   semantics of that URI scheme must be subsequently published by the
   same medium as originally employed.

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4. Security Considerations

   The vendor identified by the vendor-id part of the URI scheme name
   should be consulted for any information regarding the URI scheme and
   its implementation.  To that end, vendors must provide a point of
   contact that can be reasonably authenticated, for instance, common
   business contact information (business address, telephone number,
   etc.).  (This is addressed in the registration section above.)

   The registration process encourages vendors to analyze and disclose
   the security implications of using particular URI schemes.
   Unregistered schemes or those without appropriate security
   considerations may be unsafe to use.

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5. IANA Considerations

   IANA currently maintains a registry of URI scheme names, per the
   requirements of RFC 2717. Scheme names established under this process
   should also be entered in that registry, when requested.

   IANA should maintain a separate registry of vendor-id strings,
   relating the vendor-id to the vendor information (business contact
   information, etc.) provided in the registration. The vendor-id string
   list should be used also for vendor strings used in media types, as
   per RFC 2048.  IANA should reject a vendor-id registration if it
   duplicates an existing registration, seems inappropriate, confusing,
   misleading, or too similar to another registered vendor-id, at IANA's
   discression. IANA may offer an alternative vendor-id string that IANA
   considers more appropriate.

   A party whose vendor-id registration has been rejected or modified
   may ask for review of the registration by the IESG, in the manner
   described in RFC 2026, section 6.5.

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6. Registration forms

   Form for vendor information:

      Vendor-ID:        proposed identifier
      Name:      formal name of organization
      Address:   full name of organization
      Telephone: full telephone number
      Type:      type of organization (corporation, educational
                   institution, etc.)
      Contact Information:  name of contact person and location

   The form for scheme names follows RFC 2717, section 6.0.

       Scheme name:
       Scheme syntax:
       Character encoding considerations:
       Intended usage:
       Applications and/or protocols which use this URL scheme name:
       Interoperability considerations:
       Security considerations:
       Relevant publications:

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Normative References

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

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Informative References

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

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

   [4]  Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet
        Mail Extensions (MIME) Part Four: Registration Procedures", RFC
        2048, November 1996.

Authors' Addresses

   Ian King
   Microsoft Corporation
   One Microsoft Way
   Redmond, WA  98052-6399

   Phone: +1 425 703 2293
   EMail: iking@microsoft.com

   Larry Masinter
   Adobe Systems Incorporated
   345 Park Ave
   San Jose, CA  95110

   Phone: +1 408 536 3024
   EMail: LMM@acm.org
   URI:   http://larry.masinter.net

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