Media Types with Multiple Suffixes
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This is an older version of an Internet-Draft whose latest revision state is "Active".
|Authors||Manu Sporny , Amy Guy|
|Last updated||2022-02-16 (Latest revision 2021-12-01)|
|RFC stream||Internet Engineering Task Force (IETF)|
|Additional resources||Mailing list discussion|
|Stream||WG state||WG Document|
|Associated WG milestone||
|IESG||IESG state||AD is watching|
|Responsible AD||Murray Kucherawy|
|Send notices to||(None)|
MEDIAMAN M.S. Sporny Internet-Draft A.G. Guy Intended status: Standards Track Digital Bazaar Expires: 25 May 2022 November 2021 Media Types with Multiple Suffixes draft-ietf-mediaman-suffixes-00 Abstract This document updates RFC 6838 "Media Type Specifications and Registration Procedures" to describe how to interpret subtypes with multiple suffixes. 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 https://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 5 May 2022. Copyright Notice Copyright (c) 2021 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 (https://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 to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Sporny & Guy Expires 25 May 2022 [Page 1] Internet-Draft Media Types with Multiple Suffixes November 2021 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Conventions Used in This Document . . . . . . . . . . . . 2 2. Media Types with Multiple Suffixes . . . . . . . . . . . . . 2 2.1. Processing Multiple Suffixes . . . . . . . . . . . . . . 3 3. Normative References . . . . . . . . . . . . . . . . . . . . 3 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction As written, RFC 6838 [RFC6838] permits the registration of media type subtype names which contain any number of occurrences of the "+" character. RFC 6838 defines the characters following the final "+" to be a structured syntax suffix, but does not define anything further about how to interpret subtype names containing more than one "+" character. This document updates RFC 6838 to clarify how to interpret subtype names containing more than one "+" character as subtypes with multiple suffixes. As registration of media types which use a structured suffix has become widely supported, this enables further specialization of media types that build on already registered and well-defined media types which themselves use a structured suffix. 1.1. Conventions Used in This Document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] when they appear in ALL CAPS. They may also appear in lower or mixed case as plain English words, without any normative meaning. 2. Media Types with Multiple Suffixes The following paragraphs are additions to RFC 6838. Media types MAY be registered with more than one suffix appended to the base subtype name. The suffixes MUST be interpreted as ordered. Valid media type names containing a structured suffix are built from right to left (not left to right). Characters on the left-most side of the left-most "+" in a subtype name specify the base subtype name. Characters to the right of each "+" in a subtype name denote additional structured syntax specifier suffixes. Sporny & Guy Expires 25 May 2022 [Page 2] Internet-Draft Media Types with Multiple Suffixes November 2021 Media types with more than one suffix MUST be registered according to the procedure defined in [RFC6838]. A new base subtype name MUST only be registered with suffix combinations that are already registered in their own right. For example, a media type that uses the two suffixes "+svg+xml" is only permitted insofar as "svg+xml" is already registered. In this case, the suffix "+svg" does not need to be registered individually, but "+xml" and "svg+xml" MUST be registered. 2.1. Processing Multiple Suffixes Registered subtypes have clear processing rules. In cases where specific handling of the exact media type is not required, receivers of the media type MAY do generic processing on the underlying representation according to their ability to process any subset of the suffix(es) from right to left inclusive. In other words, an application can choose to ignore the base subtype name and left-most "+" from a media type with multiple suffixes, and process according to the remaining media type suffix(es). An application can ignore as many of the left-most suffixes as necessary to achieve a media type that can be processed. For example, for the media type "application/did+ld+json", the following are all valid subtypes with their own individually specified processing rules: did+ld+json ld+json json Thus applications can choose to process the underlying representation according any of the following valid media types: application/did+ld+json application/ld+json application/json 3. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. Sporny & Guy Expires 25 May 2022 [Page 3] Internet-Draft Media Types with Multiple Suffixes November 2021 [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type Specifications and Registration Procedures", BCP 13, RFC 6838, DOI 10.17487/RFC6838, January 2013, <https://www.rfc-editor.org/info/rfc6838>. Appendix A. Acknowledgements The editors would like to thank the following individuals for feedback on the specification (in alphabetical order): Martin J. Duerst, Ivan Herman, Graham Klyne, Murray S. Kucherawy, Manu Sporny, Ted Thibodeau Jr. Authors' Addresses Manu Sporny Digital Bazaar 203 Roanoke Street W. Blacksburg, VA 24060 United States of America Email: email@example.com URI: http://manu.sporny.org/ Amy Guy Digital Bazaar 203 Roanoke Street W. Blacksburg, VA 24060 United States of America Email: firstname.lastname@example.org URI: https://rhiaro.co.uk/ Sporny & Guy Expires 25 May 2022 [Page 4]