Internet DRAFT - draft-ietf-appsawg-media-type-suffix-regs

draft-ietf-appsawg-media-type-suffix-regs






Network Working Group                                          T. Hansen
Internet-Draft                                         AT&T Laboratories
Updates: 3023 (if approved)                                  A. Melnikov
Intended status: Informational                                 Isode Ltd
Expires: May 9, 2013                                    November 5, 2012


            Additional Media Type Structured Syntax Suffixes
              draft-ietf-appsawg-media-type-suffix-regs-08

Abstract

   A content media type name sometimes includes partitioned meta-
   information distinguish by a Structured Syntax, to permit noting an
   attribute of the media as a suffix to the name.  This document
   defines several Structured Syntax Suffixes for use with media type
   registrations.  In particular, it defines and registers the "+json",
   "+ber", "+der", "+fastinfoset", "+wbxml" and "+zip" Structured Syntax
   Suffixes, and provides a Message Type Structured Syntax Suffix
   registration form for the "+xml" Structured Syntax Suffix.

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 May 9, 2013.

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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   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.  When to Use these Structured Syntax Suffixes . . . . . . . . .  3
   3.  Initial Structured Syntax Suffix Definitions . . . . . . . . .  4
     3.1.  The +json Structured Syntax Suffix . . . . . . . . . . . .  4
     3.2.  The +ber Structured Syntax Suffixes  . . . . . . . . . . .  5
     3.3.  The +der Structured Syntax Suffixes  . . . . . . . . . . .  6
     3.4.  The +fastinfoset Structured Syntax Suffix  . . . . . . . .  8
     3.5.  The +wbxml Structured Syntax Suffix  . . . . . . . . . . .  9
     3.6.  The +zip Structured Syntax Suffix  . . . . . . . . . . . . 10
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 14
   Appendix A.  Change History  . . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15



























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1.  Introduction

   [RFC3023] created the +xml suffix convention that can be used when
   defining names for media types whose representation uses XML
   underneath.  That is, they could have been successfully parsed as if
   the media type had been application/xml in addition to their being
   parsed as their media type that is using the +xml suffix.
   [I-D.ietf-appsawg-media-type-regs] defines the Message Type
   Structured Syntax Suffixes registry to be used for such Structured
   Syntax Suffixes.

   A variety of Structured Syntax Suffixes have already been used in
   some media type registrations, in particular "+json", "+der",
   "+fastinfoset" and "+wbxml".  This document defines and registers
   these Structured Syntax Suffixes in the Structured Syntax Suffix
   registry, along with "+ber" and "+zip".  In addition, this document
   updates [RFC3023] to formally register the "+xml" Structured Syntax
   Suffix according to procedure defined in
   [I-D.ietf-appsawg-media-type-regs].

   Discussion of this document should occur in the Apps Area Working
   Group (apps-discuss@ietf.org).  [RFC Editor note: remove this
   paragraph.]

   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].


2.  When to Use these Structured Syntax Suffixes

   Each of the Structured Syntax Suffixes defined in this document is
   appropriate for use when the media type identifies the semantics of
   the protocol payload.  That is, knowing the semantics of the specific
   media type provides for more specific processing of the content than
   that afforded by generic processing of the underlying representation.

   At the same time, using the suffix allows receivers of the media
   types to do generic processing of the underlying representation in
   cases where

      they do not need to perform special handling of the particular
      semantics of the exact media type, and,

      there is no special knowledge needed by such a generic processor
      in order to parse that underlying representation other than what
      would be needed to parse any example of that underlying
      representation.



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3.  Initial Structured Syntax Suffix Definitions

3.1.  The +json Structured Syntax Suffix

   [RFC4627] defines the "application/json" media type.  The suffix
   "+json" MAY be used with any media type whose representation follows
   that established for "application/json".  The Message Type Structured
   Syntax Suffix registration form follows.  See
   [I-D.ietf-appsawg-media-type-regs] for definitions of each of the
   registration form headings.

   Name:               JavaScript Object Notation (JSON)

   +suffix:            +json

   References:         [RFC4627]

   Encoding considerations:  Per [RFC4627], JSON is allowed to be
                       represented using UTF-8, UTF-16, or UTF-32.  When
                       JSON is written in UTF-8, JSON is 8bit compatible
                       ([RFC2045]).  When JSON is written in UTF-16 or
                       UTF-32, JSON is binary ([RFC2045]).

   Fragment identifier considerations:

                          The syntax and semantics of fragment
                          identifiers specified for +json SHOULD be as
                          specified for "application/json".  (At
                          publication of this document, there is no
                          fragment identification syntax defined for
                          "application/json".)

                          The syntax and semantics for fragment
                          identifiers for a specific "xxx/yyy+json"
                          SHOULD be processed as follows:

                             For cases defined in +json, where the
                             fragment identifier resolves per the +json
                             rules, then as specified in +json.

                             For cases defined in +json, where the
                             fragment identifier does not resolve per
                             the +json rules, then as specified in "xxx/
                             yyy+json".







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                             For cases not defined in +json, then as
                             specified in "xxx/yyy+json".

   Interoperability considerations:  n/a

   Security considerations:  See [RFC4627]

   Contact:            Apps Area Working Group (apps-discuss@ietf.org)

   Author/Change controller:  The Apps Area Working Group.  IESG has
                       change control over this registration.

3.2.  The +ber Structured Syntax Suffixes

   The ITU defined the Basic Encoding Rules (BER) message transfer
   syntax in [ITU.X690.2008].  The suffix "+ber" MAY be used with any
   media type whose representation follows the BER message transfer
   syntax.  (The expert reviewer for Message Type Structured Syntax
   Suffix registrations ought to be aware of the relationship between
   BER and DER to aid in selecting the proper suffix.)  The Message Type
   Structured Syntax Suffix registration form for +ber follows:

   Name:               Basic Encoding Rules (BER) message transfer
                       syntax

   +suffix:            +ber

   References:         [ITU.X690.2008]

   Encoding considerations:  BER is a binary encoding.

   Fragment identifier considerations:

                          At publication of this document, there is no
                          fragment identification syntax defined for
                          +ber.

                          The syntax and semantics for fragment
                          identifiers for a specific "xxx/yyy+ber"
                          SHOULD be processed as follows:

                             For cases defined in +ber, where the
                             fragment identifier resolves per the +ber
                             rules, then as specified in +ber.







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                             For cases defined in +ber, where the
                             fragment identifier does not resolve per
                             the +ber rules, then as specified in "xxx/
                             yyy+ber".

                             For cases not defined in +ber, then as
                             specified in "xxx/yyy+ber".

   Interoperability considerations:  n/a

   Security considerations:  Each individual media type registered with
                       a +ber suffix can have additional security
                       considerations.

                       BER has a type-length-value structure, and it is
                       easy to construct malicious content with invalid
                       length fields that can cause buffer overrun
                       conditions.

                       BER allows for arbitrary levels of nesting, which
                       may make it possible to construct malicious
                       content that will cause a stack overflow.

                       Interpreters of the BER structures should be
                       aware of these issues and should take appropriate
                       measures to guard against buffer overflows and
                       stack overruns in particular and malicious
                       content in general.

   Contact:            Apps Area Working Group (apps-discuss@ietf.org)

   Author/Change controller:  The Apps Area Working Group.  IESG has
                       change control over this registration.

3.3.  The +der Structured Syntax Suffixes

   The ITU defined the Distinguished Encoding Rules (DER) message
   transfer syntax in [ITU.X690.2008].  The suffix "+der" MAY be used
   with any media type whose representation follows the DER message
   transfer syntax.  (The expert reviewer for Message Type Structured
   Syntax Suffix registrations ought to be aware of the relationship
   between BER and DER to aid in selecting the proper suffix.)  The
   Message Type Structured Syntax Suffix registration form for +der
   follows:







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   Name:               Distinguished Encoding Rules (DER) message
                       transfer syntax

   +suffix:            +der

   References:         [ITU.X690.2008]

   Encoding considerations:  DER is a binary encoding.

   Fragment identifier considerations:

                          At publication of this document, there is no
                          fragment identification syntax defined for
                          +der.

                          The syntax and semantics for fragment
                          identifiers for a specific "xxx/yyy+der"
                          SHOULD be processed as follows:

                             For cases defined in +der, where the
                             fragment identifier resolves per the +der
                             rules, then as specified in +der.

                             For cases defined in +der, where the
                             fragment identifier does not resolve per
                             the +der rules, then as specified in "xxx/
                             yyy+der".

                             For cases not defined in +der, then as
                             specified in "xxx/yyy+der".

   Interoperability considerations:  n/a

   Security considerations:  Each individual media type registered with
                       a +der suffix can have additional security
                       considerations.

                       DER has a type-length-value structure, and it is
                       easy to construct malicious content with invalid
                       length fields that can cause buffer overrun
                       conditions.

                       DER allows for arbitrary levels of nesting, which
                       may make it possible to construct malicious
                       content that will cause a stack overflow.






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                       Interpreters of the DER structures should be
                       aware of these issues and should take appropriate
                       measures to guard against buffer overflows and
                       stack overruns in particular and malicious
                       content in general.

   Contact:            Apps Area Working Group (apps-discuss@ietf.org)

   Author/Change controller:  The Apps Area Working Group.  IESG has
                       change control over this registration.

3.4.  The +fastinfoset Structured Syntax Suffix

   The ITU defined the Fast Infoset document format as a binary
   representation of the XML Information Set in [ITU.X891.2005].  These
   documents further define the "application/fastinfoset" media type.
   The suffix "+fastinfoset" MAY be used with any media type whose
   representation follows that established for "application/
   fastinfoset".  The Message Type Structured Syntax Suffix registration
   form follows:

   Name:               Fast Infoset document format

   +suffix:            +fastinfoset

   References:         [ITU.X891.2005]

   Encoding considerations:  Fast Infoset is a binary encoding.  The
                       binary, quoted-printable and base64 content-
                       transfer-encodings are suitable for use with Fast
                       Infoset.

   Fragment identifier considerations:

                          The syntax and semantics of fragment
                          identifiers specified for +fastinfoset SHOULD
                          be as specified for "application/fastinfoset".
                          (At publication of this document, there is no
                          fragment identification syntax defined for
                          "application/fastinfoset".)

                          The syntax and semantics for fragment
                          identifiers for a specific "xxx/
                          yyy+fastinfoset" SHOULD be processed as
                          follows:






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                             For cases defined in +fastinfoset, where
                             the fragment identifier resolves per the
                             +fastinfoset rules, then as specified in
                             +fastinfoset.

                             For cases defined in +fastinfoset, where
                             the fragment identifier does not resolve
                             per the +fastinfoset rules, then as
                             specified in "xxx/yyy+fastinfoset".

                             For cases not defined in +fastinfoset, then
                             as specified in "xxx/yyy+fastinfoset".

   Interoperability considerations:  n/a

   Security considerations:  There are no security considerations
                       inherent in Fast Infoset.  Each individual media
                       type registered with a +fastinfoset suffix can
                       have additional security considerations.

   Contact:            Apps Area Working Group (apps-discuss@ietf.org)

   Author/Change controller:  The Apps Area Working Group.  IESG has
                       change control over this registration.

3.5.  The +wbxml Structured Syntax Suffix

   The WAP Forum has defined the WAP Binary XML (WBXML) document format
   as a binary representation of XML in [WBXML].  This document further
   defines the "application/vnd.wap.wbxml" media type.  The suffix
   "+wbxml" MAY be used with any media type whose representation follows
   that established for "application/vnd.wap.wbxml".  The Message Type
   Structured Syntax Suffix registration form follows:

   Name:               WAP Binary XML (WBXML) document format

   +suffix:            +wbxml

   References:         [WBXML]

   Encoding considerations:  WBXML is a binary encoding.

   Fragment identifier considerations:

                          The syntax and semantics of fragment
                          identifiers specified for +wbxml SHOULD be as
                          specified for "application/vnd.wap.wbxml".
                          (At publication of this document, there is no



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                          fragment identification syntax defined for
                          "application/vnd.wap.wbxml".)

                          The syntax and semantics for fragment
                          identifiers for a specific "xxx/yyy+wbxml"
                          SHOULD be processed as follows:

                             For cases defined in +wbxml, where the
                             fragment identifier resolves per the +wbxml
                             rules, then as specified in +wbxml.

                             For cases defined in +wbxml, where the
                             fragment identifier does not resolve per
                             the +wbxml rules, then as specified in
                             "xxx/yyy+wbxml".

                             For cases not defined in +wbxml, then as
                             specified in "xxx/yyy+wbxml".

   Interoperability considerations:  n/a

   Security considerations:  There are no security considerations
                       inherent in WBXML.  Each individual media type
                       registered with a +wbxml suffix can have
                       additional security considerations.

   Contact:            Apps Area Working Group (apps-discuss@ietf.org)

   Author/Change controller:  The Apps Area Working Group.  IESG has
                       change control over this registration.

3.6.  The +zip Structured Syntax Suffix

   The ZIP format is a public domain, cross-platform, interoperable file
   storage and transfer format, originally defined by PKWARE, Inc.; it
   supports compression and encryption and is used as the underlying
   representation by a variety of file formats.  The media type
   "application/zip" has been registered for such files.  The suffix
   "+zip" MAY be used with any media type whose representation follows
   that established for "application/zip".  The Message Type Structured
   Syntax Suffix registration form follows:

   Name:               ZIP file storage and transfer format

   +suffix:            +zip






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   References:         [ZIP]

   Encoding considerations:  ZIP is a binary encoding.

   Fragment identifier considerations:

                          The syntax and semantics of fragment
                          identifiers specified for +zip SHOULD be as
                          specified for "application/zip".  (At
                          publication of this document, there is no
                          fragment identification syntax defined for
                          "application/zip".)

                          The syntax and semantics for fragment
                          identifiers for a specific "xxx/yyy+zip"
                          SHOULD be processed as follows:

                             For cases defined in +zip, where the
                             fragment identifier resolves per the +zip
                             rules, then as specified in +zip.

                             For cases defined in +zip, where the
                             fragment identifier does not resolve per
                             the +zip rules, then as specified in "xxx/
                             yyy+zip".

                             For cases not defined in +zip, then as
                             specified in "xxx/yyy+zip".

   Interoperability considerations:  n/a

   Security considerations:  ZIP files support two forms of encryption:
                       Strong Encryption and AES 128-bit, 192-bit and
                       256-bit encryption; see the specification for
                       further details.  Each individual media type
                       registered with a +zip suffix can have additional
                       security considerations.

   Contact:            Apps Area Working Group (apps-discuss@ietf.org)

   Author/Change controller:  The Apps Area Working Group.  IESG has
                       change control over this registration.


4.  IANA Considerations

   See the Message Type Structured Syntax Suffix registration forms in
   Section 3.1 - Section 3.6.



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   The following Structured Syntax Suffix registration for "+xml" shall
   be used to reflect the information found in [RFC3023], with the
   addition of fragment identifier considerations:

   Name:               Extensible Markup Language (XML)

   +suffix:            +xml

   References:         [RFC3023]

   Encoding considerations:  Per [RFC3023], XML is allowed to be
                       represented using both 7-bit and 8-bit encodings.
                       When XML is written in UTF-8, XML is 8bit
                       compatible ([RFC2045]).  When XML is written in
                       UTF-16 or UTF-32, XML is binary ([RFC2045]).

   Fragment identifier considerations:

                          The syntax and semantics of fragment
                          identifiers specified for +xml SHOULD be as
                          specified for "application/xml".  (At
                          publication of this document, the fragment
                          identification syntax considerations for
                          "application/xml" are defined in [RFC3023],
                          sections 5 and 7.)

                          The syntax and semantics for fragment
                          identifiers for a specific "xxx/yyy+xml"
                          SHOULD be processed as follows:

                             For cases defined in +xml, where the
                             fragment identifier resolves per the +xml
                             rules, then as specified in +xml.

                             For cases defined in +xml, where the
                             fragment identifier does not resolve per
                             the +xml rules, then as specified in "xxx/
                             yyy+xml".

                             For cases not defined in +xml, then as
                             specified in "xxx/yyy+xml".

   Interoperability considerations:  See [RFC3023].

   Security considerations:  See [RFC3023]






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   Contact:            Apps Area Working Group (apps-discuss@ietf.org)

   Author/Change controller:  The Apps Area Working Group.  IESG has
                       change control over this registration.


5.  Security Considerations

   See the Security considerations sections found in the Message Type
   Structured Syntax Suffix registration forms from Section 3.1 -
   Section 3.5.

   When updating a +<suffix> registration, care should be taken to
   review all previously-registered xxx/yyy+<suffix> media types as to
   whether they might be affected by the updated +<suffix> registration.
   Because the generic fragment identifier processing rules take
   precedence over media-type-specific rules, introducing new or
   changing existing definitions may break the existing registrations of
   specific media types, as well as particular implementations of
   applications that process affected media types.  Such changes can
   introduce interoperability and security issues.

   When updating the fragment identifier processing rules for a specific
   xxx/yyy+<suffix> media type, care should be taken to review the
   generic fragment identifier processing rules for the +<suffix>
   registration and not introduce any conflicts.  Because the generic
   fragment identifier processing rules take precedence over media-type-
   specific rules, such conflicting processing requirements should be
   ignored by an implementation, but such conflicts can introduce
   interoperability and security issues.

   Note that [FRAGID-BP] provides additional advice to designers of
   fragment identifier rules for media type suffixes and specific media
   types.


6.  References

6.1.  Normative References

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.

   [ITU.X690.2008]
              International Telecommunications Union, "Recommendation
              ITU-T X.690 | ISO/IEC 8825-1 (2008), ASN.1 encoding rules:
              Specification of basic encoding Rules (BER), Canonical
              encoding rules (CER) and Distinguished encoding rules



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              (DER)", ITU-T Recommendation X.690, November 2008.

   [ITU.X891.2005]
              International Telecommunications Union, "Recommendation
              ITU-T X.891 | ISO/IEC 24824-1 (2007), Generic applications
              of ASN.1: Fast infoset", ITU-T Recommendation X.891,
              May 2005.

   [WBXML]    Open Mobile Alliance, "Binary XML Content Format
              Specification", OMA Wireless Access Protocol WAP-192-
              WBXML-20010725-a, July 2001.

   [ZIP]      PKWARE, Inc., "APPNOTE.TXT - .ZIP File Format
              Specification", PKWARE .ZIP File Format Specification -
              Version 6.3.2, September 2007.

   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, November 1996.

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

   [RFC3023]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media
              Types", RFC 3023, January 2001.

6.2.  Informative References

   [I-D.ietf-appsawg-media-type-regs]
              Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures",
              draft-ietf-appsawg-media-type-regs-14 (work in progress),
              June 2012.

   [FRAGID-BP]
              Tennison, J., "Best Practices for Fragment Identifiers and
              Media Type Definitions", July 2012,
              <http://www.w3.org/TR/fragid-best-practices/>.


Appendix A.  Change History

   This section is to be removed before publication.

   draft-ietf-appsawg-media-type-suffix-regs-07  Added information based
                       on IANA and GEN-ART reviews.





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   draft-ietf-appsawg-media-type-suffix-regs-06  Clarified why this
                       document updates RFC 3023.

   draft-ietf-appsawg-media-type-suffix-regs-05  Added an Informative
                       reference to
                       http://www.w3.org/TR/fragid-best-practices/.
                       Minor editorial changes.

   draft-ietf-appsawg-media-type-suffix-regs-03  Added generic fragment
                       idenfier rules to +ber/+der to make them
                       consistant with other registrations.
                       Added some warning about how adding/changing
                       fragment identifier rules for a +suffix can
                       affect fragment identifier processing rules for
                       previously registered xxx/yyy+suffix media types.

   draft-ietf-appsawg-media-type-suffix-regs-02  Added BER/DER security
                       considerations.
                       Reworked fragment identifier wording some more.

   draft-ietf-appsawg-media-type-suffix-regs-01  Reordered the sections.
                       Cleaned up some MUSTard.
                       Fixed some references.
                       Added encoding considerations.
                       Reworked fragment identifier wording.

   draft-ietf-appsawg-media-type-suffix-regs-00  Added the fragment
                       identifier consideration sections.
                       Added a note about +xml fragment identifier
                       considerations.

   draft-hansen-media-type-suffix-regs-02  Added +zip.
                       Fixed up the ISO document references.
                       Minor changes.

   draft-hansen-media-type-suffix-regs-01  Added +ber.
                       Minor changes.














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Authors' Addresses

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

   Email: tony+sss@maillennium.att.com


   Alexey Melnikov
   Isode Ltd
   5 Castle Business Village
   36 Station Road
   Hampton, Middlesex  TW12 2BX
   UK

   Email: Alexey.Melnikov@isode.com
































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