encoding
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... Transfer Encodings ...
...
Transfer encodings are transformations applied to MIME media types
after conversion to the media type ...
... after conversion to the media type's canonical form. Transfer
encodings are used for several purposes:
o Many transports ...
... ASCII, and others cannot handle certain character sequences.
Transfer encodings are used to transform binary data into a
textual form that can survive such transports ...
... textual form that can survive such transports. Examples of this
sort of transfer encoding include the base64 and quoted-printable
transfer encodings defined in [RFC2045 ...
... sort of transfer encoding include the base64 and quoted-printable
transfer encodings defined in [RFC2045].
...
... quite large. Compression algorithms are often effective in
reducing the size of large entities. Transfer encodings can be
used to apply general-purpose non-lossy compression algorithms to
...
... MIME entities.
o Transport encodings can be defined as a means of representing
existing encoding formats in a MIME ...
... o Transport encodings can be defined as a means of representing
existing encoding formats in a MIME context.
...
...
IMPORTANT: The standardization of a large number of different
transfer encodings is seen as a significant barrier to widespread
interoperability and is expressly discouraged. Nevertheless, the
...
... interoperability and is expressly discouraged. Nevertheless, the
following procedure has been defined in order to provide a means of
defining additional transfer encodings, should standardization
actually be justified.
...
... Transfer Encoding Requirements ...
...
Transfer encoding specifications MUST conform to the requirements
described below.
...
...
Each transfer encoding MUST have a unique name. This name appears in
the Content-Transfer-Encoding header field ...
... Each transfer encoding MUST have a unique name. This name appears in
the Content-Transfer-Encoding header field and MUST conform to the
syntax of that field.
...
...
All of the algorithms used in a transfer encoding (e.g., conversion
to printable form, compression) MUST be described in their entirety
...
... to printable form, compression) MUST be described in their entirety
in the transfer encoding specification. Use of secret and/or
...
...
proprietary algorithms in standardized transfer encodings is
expressly prohibited. The restrictions imposed by [RFC2026] on the
...
...
All transfer encodings MUST be applicable to an arbitrary sequence of
octets of any length. Dependence on particular input forms is not
allowed.
...
...
It should be noted that the 7bit and 8bit encodings do not conform to
this requirement. Aside from the undesirability of having
...
... this requirement. Aside from the undesirability of having
specialized encodings, the intent here is to forbid the addition of
additional encodings similar to, or redundant with, 7bit and 8bit ...
... specialized encodings, the intent here is to forbid the addition of
additional encodings similar to, or redundant with, 7bit and 8bit.
...
...
There is no requirement that a particular transfer encoding produce a
particular form of encoded output. However, the output format for
each transfer encoding ...
... transfer encoding produce a
particular form of encoded output. However, the output format for
each transfer encoding MUST be fully and completely documented. In
particular, each specification MUST clearly state whether the output
...
...
All transfer encodings MUST be fully invertible on any platform; it
MUST be possible for anyone to recover the original data by
performing the corresponding decoding operation. Note that this
...
...
All transfer encodings MUST provide some sort of new functionality.
Some degree of functionality overlap with previously defined transfer
encodings is acceptable, but any new transfer encoding ...
... All transfer encodings MUST provide some sort of new functionality.
Some degree of functionality overlap with previously defined transfer
encodings is acceptable, but any new transfer encoding MUST also
offer something no other transfer encoding ...
... transfer encodings MUST provide some sort of new functionality.
Some degree of functionality overlap with previously defined transfer
encodings is acceptable, but any new transfer encoding MUST also
offer something no other transfer encoding provides.
...
... transfer
encodings is acceptable, but any new transfer encoding MUST also
offer something no other transfer encoding provides.
...
...
To the greatest extent possible, transfer encodings SHOULD NOT
contain known security issues. Regardless, any known security issues ...
... security issues. Regardless, any known security issues
that arise from the use of the transfer encoding MUST be completely
and fully described. If additional security issues come to light
...
... registration, they SHOULD be addressed
by publishing revised versions of the transfer encoding
specification.
...
...
Definition of a new transfer encoding starts with the publication of
the specification as an Internet Draft ...
... the specification as an Internet Draft. The draft MUST define the
transfer encoding precisely and completely, and it MUST also provide
substantial justification for defining and standardizing a new
transfer encoding ...
... transfer encoding precisely and completely, and it MUST also provide
substantial justification for defining and standardizing a new
transfer encoding. This specification MUST then be presented to the
IESG for consideration. The IESG ...
... standards-track submission.
Transfer encoding specifications on the standards track follow normal
IETF rules for standards-track documents ...
... IETF rules for standards-track documents. A transfer encoding is
considered to be defined and available for use once it is on the
...
... IANA Procedures for Transfer Encoding Registration ...
...
There is no need for a special procedure for registering Transfer
Encodings with the IANA. All legitimate transfer encoding
registrations MUST appear as a standards-track RFC ...
... There is no need for a special procedure for registering Transfer
Encodings with the IANA. All legitimate transfer encoding
registrations MUST appear as a standards-track RFC, so it is the
IESG's ...
...
The list of transfer encoding registrations can be found at:
http://www.iana.org/assignments/transfer-encodings ...
... transfer encoding registrations can be found at:
http://www.iana.org/assignments/transfer-encodings
...
... access types are discussed in Section
2.1.4. Security requirements for transfer encodings are discussed in
Section 3.1.7.
...
... IANA registries for
access types and transfer encodings. The IANA procedures for these
registries ...
... current versions of the relevant specifications.
o The option of assigning the task of working on a new transfer
encoding to an existing working group has been added to the list
of possible actions the IESG ...