media type
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... specified, and public manner.
This document defines media type specification and registration
procedures that use the Internet Assigned Numbers Authority (IANA ...
... Historical Note
The media type registration process was initially defined for
registering media types for use in the context ...
... The media type registration process was initially defined for
registering media types for use in the context of the asynchronous
...
... Internet mail environment. In this mail environment there is a
need to limit the number of possible media types, to increase the
likelihood of interoperability when the capabilities of the remote
...
... interoperability when the capabilities of the remote
mail system are not known. As media types are used in new
environments in which the proliferation of media types is not a
...
... mail system are not known. As media types are used in new
environments in which the proliferation of media types is not a
hindrance to interoperability, the original procedure proved
...
... RFC2048], but the procedure defined there was
still part of the MIME document set. The media type specification
and registration procedure has now been moved to this separate
...
... MIME.
It may be desirable to restrict the use of media types to specific
environments or to prohibit their use in other environments. This
revision attempts for the first time to incorporate such
...
... environments or to prohibit their use in other environments. This
revision attempts for the first time to incorporate such
restrictions into media type registrations in a systematic way.
See Section 4.9 for additional discussion.
...
...
Registration of a new media type or types starts with the
construction of a registration proposal ...
... registration
proposal is circulated and reviewed in a fashion appropriate to the
tree involved. The media type is then registered if the proposal is
acceptable. The following sections describe the requirements and
...
... "tree.subtree...subtype". Note that some media types defined prior
to this document do not conform to the naming conventions described
below. See Appendix A for a discussion ...
... general specification of some sort.
Media types in the standards tree are normally denoted by names that
are not explicitly faceted, i.e., do not contain period (".", full
...
... stop) characters.
The "owner" of a media type registration in the standards tree is
assumed to be the standards body itself. Modification or alteration
...
...
The vendor tree is used for media types associated with commercially
available products. "Vendor" or "producer ...
... IANA-approved designation of the
producer's name that is followed by a media type or product
designation (e.g., vnd.bigcompany.funnypictures).
...
... designation (e.g., vnd.bigcompany.funnypictures).
While public exposure and review of media types to be registered in
the vendor tree is not required, using the ietf-types ...
...
Registrations for media types created experimentally or as part of
products that are not distributed commercially may be registered in
...
... responsibility has been transferred as described below.
While public exposure and review of media types to be registered in
the personal tree is not required, using the ietf-types ...
... permanent bodies; for example, scientific societies may register
media types specific to the sciences they cover. In general, the
quality of review of specifications for one of these additional
registration trees is expected to be equivalent to registrations ...
...
Media type registration proposals are all expected to conform to
various requirements laid out in the following sections. Note that
...
...
All registered media types MUST be assigned type and subtype names.
The combination of these names serves to uniquely identify the media
type ...
... registered media types MUST be assigned type and subtype names.
The combination of these names serves to uniquely identify the media
type, and the format of the subtype name identifies the registration
tree. Both type and subtype names ...
... suffix definitions.
While it is possible for a given media type to be assigned additional
names, the use of different names to identify the same media type is
...
... While it is possible for a given media type to be assigned additional
names, the use of different names to identify the same media type is
discouraged.
...
... The choice of top-level type name MUST take into account the nature
of media type involved. New subtypes of top-level types MUST conform
to the restrictions of the top-level type ...
... including but not limited to MIME, MAY impose additional restrictions
on the media types they can transport. (See [RFC2046] for additional
...
... Text Media Types ...
...
The "text" media type is intended for sending material that is
principally textual in form. A "charset" parameter MAY be used to
...
... Image Media Types ...
... Audio Media Types ...
... Video Media Types ...
...
A media type of "video" indicates that the content specifies a time-
varying-picture image, possibly with color and coordinated sound ...
... Application Media Types ...
...
The "application" media type is to be used for discrete data that do
not fit in any of the media types, and particularly for data to be
...
... The "application" media type is to be used for discrete data that do
not fit in any of the media types, and particularly for data to be
processed by some type of application program. This is information
that must be processed by an application before it is viewable or
...
... processed by some type of application program. This is information
that must be processed by an application before it is viewable or
usable by a user. Expected uses for the "application" media type
include but are not limited to file transfer, spreadsheets,
...
... transported to a remote location and automatically run in the
recipient's environment. Such applications may be defined as
subtypes of the "application" media type.
The subtype of "application" will often be either the name or include
...
... Multipart and Message Media Types ...
... composite types, that is, they provide a
means of encapsulating zero or more objects, each labeled with its
own media type.
All subtypes of multipart and message MUST conform to the syntax
...
...
In some cases a new media type may not "fit" under any currently
defined top-level content type ...
...
Media types MAY elect to use one or more media type parameters, or
some parameters may be automatically made available to the media type ...
...
Media types MAY elect to use one or more media type parameters, or
some parameters may be automatically made available to the media type
...
... Media types MAY elect to use one or more media type parameters, or
some parameters may be automatically made available to the media type
by virtue of being a subtype of a content type that defines a set of
...
... names, values, and meanings of any parameters MUST be fully specified
when a media type is registered in the standards tree, and SHOULD be
specified as completely as possible when media types ...
... media type is registered in the standards tree, and SHOULD be
specified as completely as possible when media types are registered
in the vendor or personal trees ...
... personal trees.
Parameter names have the syntax as media type names and values:
parameter-name ...
... external specification such as JPEG. Similar behavior is encouraged
for media types registered in the vendor or personal trees but is not
...
...
All registered media types MUST employ a single, canonical data
format, regardless of registration tree.
...
...
A precise and openly available specification of the format of each
media type MUST exist for all types registered in the standards tree
and MUST at a minimum be referenced by, if it isn't actually included
...
... standards tree
and MUST at a minimum be referenced by, if it isn't actually included
in, the media type registration proposal itself.
The specifications of format and processing particulars may or may
...
...
The specifications of format and processing particulars may or may
not be publicly available for media types registered in the vendor
tree, and such registration proposals are explicitly permitted to
...
... limit specification to which software and version produce or process
such media types. References to or inclusion of format
specifications in registration proposals is encouraged but not
...
... and, in particular, need not be made public.
Some media types involve the use of patented technology. The
registration of media types ...
... media types involve the use of patented technology. The
registration of media types involving patented technology is
specifically permitted. However, the restrictions set forth in
[RFC2026 ...
... RFC2026] on the use of patented technology in IETF standards-track
protocols must be respected when the specification of a media type is
part of a standards-track protocol. In addition, other standards
...
...
Media types SHOULD interoperate across as many systems and
applications as possible. However, some media types will inevitably
...
... Media types SHOULD interoperate across as many systems and
applications as possible. However, some media types will inevitably
have problems interoperating across different platforms. Problems
with different versions ...
...
Universal interoperability of media types is not required, but known
interoperability issues SHOULD be identified whenever possible.
...
... interoperability issues SHOULD be identified whenever possible.
Publication of a media type does not require an exhaustive review of
interoperability, and the interoperability ...
... analysis of security issues MUST be done for all types registered
in the standards Tree. A similar analysis for media types registered
in the vendor or personal trees ...
...
There is absolutely no requirement that media types registered in any
tree be secure or completely free from risks. Nevertheless, all
...
... security risks MUST be identified in the registration of a
media type, again regardless of registration tree.
...
... subject
to continuing evaluation and modification, and in particular MAY be
extended by use of the "comments on media types" mechanism described
in Section 6 below.
...
... Some of the issues that should be looked at in a security analysis of
a media type are:
o Complex media types ...
... media type are:
o Complex media types may include provisions for directives that
institute actions on a recipient's files or other resources. In
many cases provision is made for originators to specify arbitrary
...
... effects. See the registration of the application/postscript media
type in [RFC2046] for an example of such directives and how they
should be described in a media type registration ...
... media
type in [RFC2046] for an example of such directives and how they
should be described in a media type registration.
o All registrations ...
... active content", and if they do, they MUST state what steps have
been taken to protect users of the media type from harm.
o Complex media types ...
... media type from harm.
o Complex media types may include provisions for directives that
institute actions that, while not directly harmful to the
recipient, may result in disclosure of information that either
...
... registration of the
application/postscript media type illustrates how such directives
can be handled.
...
... can be handled.
o A media type that employs compression may provide an opportunity
for sending a small amount of data that, when received and
...
... for sending a small amount of data that, when received and
evaluated, expands enormously to consume all of the recipient's
resources. All media types SHOULD state whether or not they
employ compression ...
... attacks.
o A media type might be targeted for applications that require some
sort of security assurance but not provide the necessary security
mechanisms ...
... sort of security assurance but not provide the necessary security
mechanisms themselves. For example, a media type could be defined
for storage of confidential medical information that in turn
...
... Requirements specific to XML media types ...
... requirements specific to the
registration of XML media types. These requirements are specified in
[RFC3023 ...
... transport limitations.
It is therefore useful to note what sort of data a media type can
consist of as part of its registration. An "encoding considerations ...
... are:
7bit: The content of the media type consists solely of CRLF-delimited
7bit US-ASCII text ...
... but not necessarily limited to, knowledge of the boundaries
between successive frames and knowledge of the transport
mechanism. Note that media types of this sort cannot simply be
stored in a file or transported as a simple stream of octets;
...
... stored in a file or transported as a simple stream of octets;
therefore, such media types are unsuitable for use in many
traditional protocols. A commonly used transport with framed
...
... sender, maximum interoperability is attained by restricting the
media types used to those "common" formats expected to be widely
implemented. This was asserted in the past as a reason to limit the
number of possible media types ...
... media types used to those "common" formats expected to be widely
implemented. This was asserted in the past as a reason to limit the
number of possible media types, and it resulted in a registration
process with a significant hurdle and delay for those registering
media types ...
... media types, and it resulted in a registration
process with a significant hurdle and delay for those registering
media types.
However, the need for "common" media types ...
... media types.
However, the need for "common" media types does not require limiting
the registration of new media types ...
... media types does not require limiting
the registration of new media types. If a limited set of media types
is recommended for a particular application, that should be asserted
...
... the registration of new media types. If a limited set of media types
is recommended for a particular application, that should be asserted
by a separate applicability statement ...
... and/or environment.
Therefore, universal support and implementation of a media type is
NOT a requirement for registration ...
... NOT a requirement for registration. However, if a media type is
explicitly intended for limited use, this MUST be noted in its
registration ...
... IETF itself MUST be published as RFCs. RFC publication of vendor and
personal media type proposals is encouraged but not required. In all
cases the IANA will retain copies of all media type ...
... media type proposals is encouraged but not required. In all
cases the IANA will retain copies of all media type proposals and
"publish" them as part of the media types registration tree ...
... IANA will retain copies of all media type proposals and
"publish" them as part of the media types registration tree itself.
...
... As stated previously, standards tree registrations for media types
defined in documents produced by other standards bodies MUST be
described by a formal standards specification produced by that body.
...
... defined in documents produced by other standards bodies MUST be
described by a formal standards specification produced by that body.
Such specifications MUST contain an appropriate media type
registration template taken from Section 10. Additionally, the
copyright on the registration template MUST allow the IANA ...
... too difficult and too lengthy a process for the convenient
registration of media types.
The standards tree ...
...
The standards tree exists for media types that do require a
substantive review and approval process in a recognized standards
body. The vendor ...
... body. The vendor and personal trees exist for those media types that
do not require such a process. It is expected that applicability
statements for particular applications will be published from time to
...
... time in the IETF, recommending implementation of, and support for,
media types that have proven particularly useful in those contexts.
...
...
Various sorts of optional information SHOULD be included in the
specification of a media type if it is available:
o Magic number ...
... Magic numbers are byte
sequences that are always present at a given place in the file and
thus can be used to identify entities as being of a given media
type.
o File name extension(s) commonly used on one or more platforms to
...
...
o File name extension(s) commonly used on one or more platforms to
indicate that some file contains a given media type.
o Mac OS ...
... File Type code(s) (4 octets) used to label files containing
a given media type.
o Information about how fragment ...
... RFC3986] are
constructed for use in conjunction with this media type.
In the case of a registration ...
... registration in the standards tree, this additional
information MAY be provided in the formal specification of the media
type. It is suggested that this be done by incorporating the IANA
media type registration ...
... media
type. It is suggested that this be done by incorporating the IANA
media type registration form into the specification itself.
...
...
The media type registration procedure is not a formal standards
process, but rather an administrative procedure intended to allow
community comment and sanity checking without excessive time delay.
...
...
Notice of a potential media type registration in the standards tree
MUST be sent to the "ietf-types ...
...
Provided that the media type meets all of the relevant requirements
and has obtained whatever approval is necessary, the author may
...
... Media Types Reviewer ...
... Registrations submitted to the IANA will be passed on to the media
types reviewer. The media types reviewer, who is appointed by the
IETF ...
... Registrations submitted to the IANA will be passed on to the media
types reviewer. The media types reviewer, who is appointed by the
IETF Applications Area Director ...
... the submitter for revision.
Decisions made by the media types reviewer may be appealed to the
IESG using the procedure specified in [RFC2026 ...
... RFC2026] section 6.5.4.
Once a media type registration has passed review, the IANA will
register ...
... IANA will
register the media type and make the media type registration
available to the community.
...
... Comments on Media Type Registrations ...
...
Comments on registered media types may be submitted by members of the
community to the IANA. These comments will be reviewed by the media
types ...
... registered media types may be submitted by members of the
community to the IANA. These comments will be reviewed by the media
types reviewer and then passed on to the "owner" of the media type if
possible. Submitters of comments may request that their comment be
...
... community to the IANA. These comments will be reviewed by the media
types reviewer and then passed on to the "owner" of the media type if
possible. Submitters of comments may request that their comment be
attached to the media type registration ...
... media type if
possible. Submitters of comments may request that their comment be
attached to the media type registration itself, and if the IANA
approves of this, the comment will be made accessible in conjunction ...
...
Media type registrations are listed by the IANA at:
...
... IANA Procedures for Registering Media Types ...
... The IANA will only register media types in the standards tree in
response to a communication from the IESG ...
... process as long as the following minimal conditions are met:
o Media types MUST function as an actual media format. In
particular, charsets ...
... media types.
o All media types MUST have properly formed type and subtype names.
All type names MUST be defined by a standards-track RFC ...
... specification or a pointer to one.
o All media types MUST have a reasonable security considerations
section. (It is neither possible nor necessary for the IANA ...
... IANA to
conduct a comprehensive security review of media type
registrations. Nevertheless, the IANA has the authority to
...
...
Once a media type has been published by the IANA, the owner may
request a change to its definition. The descriptions of the
...
... under the previous definition invalid under the new definition.
The owner of a media type may pass responsibility to another person
or agency by informing the IANA and the ietf-types ...
...
The IESG may reassign responsibility for a media type. The most
common case of this will be to enable changes to be made to types
where the author of the registration ...
... Media type registrations may not be deleted; media types that are no
longer believed appropriate for use can be declared OBSOLETE by a
change to their "intended use" field; such media types ...
... media types that are no
longer believed appropriate for use can be declared OBSOLETE by a
change to their "intended use" field; such media types will be
clearly marked in the lists published by the IANA.
...
... Published specification:
Applications that use this media type:
Additional information:
...
... Restrictions on usage:
(Any restrictions on where the media type can be used go here.)
Author:
...
...
Security requirements for media type registrations are discussed in
Section 4.6.
...
...
The purpose of this document is to define IANA registries for media
types.
...
... Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046draft, November 1996. ...
... Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023prop, January 2001. ...
... Appendix A. Grandfathered Media Types ...
...
A number of media types, registered prior to 1996, would, if
registered under the guidelines in this document, be placed into
either the vendor ...
... other standards bodies.
o The text describing the media type registration procedure has
clarified.
...
... 3023prop is now referenced as the source of additional information
concerning the registration of XML media types.
o Several of the references in this document have been updated to
...
...
o A note has been added discouraging the assignment of multiple
names to a single media type.
o Security considerations ...
... added.
o Concerns regarding copyrights on media type registration templates
produced by other standards bodies have been dealt with by
requiring that the IANA ...
... 2046draft to this document.
o A syntax is now specified for media type, subtype, and parameter
names.
...
... names.
o Imposed a maximum length of 127 on all media type and subtype
names.
...