transfer-encoding
Click on the red underlined text to get to the source
... specifies that such encodings will be indicated by a new "Content-
Transfer-Encoding" header field. This field has not been defined by
any previous standard.
...
... Content-Transfer-Encoding Syntax ...
...
The Content-Transfer-Encoding field's value is a single token
specifying the type of encoding ...
... "Content-Transfer-Encoding" ":" mechanism ...
... encoding type of 7BIT requires that the body
is already in a 7bit mail-ready representation. This is the default
value -- that is, "Content-Transfer-Encoding: 7BIT" is assumed if the
Content-Transfer-Encoding header field ...
... default
value -- that is, "Content-Transfer-Encoding: 7BIT" is assumed if the
Content-Transfer-Encoding header field is not present.
...
... Content-Transfer-Encodings Semantics ...
...
This single Content-Transfer-Encoding token actually provides two
pieces of information. It specifies what sort of encoding ...
...
The transformation part of any Content-Transfer-Encodings specifies,
either explicitly or implicitly, a single, well-defined decoding
...
...
The Content-Transfer-Encoding values "7bit", "8bit", and "binary" all
mean that the identity ...
...
The proper Content-Transfer-Encoding label must always be used.
Labelling unencoded data containing 8bit characters as "7bit" is not
...
...
Unlike media subtypes, a proliferation of Content-Transfer-Encoding
values is both undesirable and unnecessary. However, establishing
only a single transformation into the "7bit" domain ...
... unencoded binary data in mail bodies. Thus there are no
circumstances in which the "binary" Content-Transfer-Encoding is
actually valid in Internet mail ...
...
NOTE: The five values defined for the Content-Transfer-Encoding field
imply nothing about the media type other than the algorithm ...
... New Content-Transfer-Encodings ...
... Encoding: x-my-new-encoding". Additional standardized Content-
Transfer-Encoding values must be specified by a standards-track RFC.
The requirements ...
... requirements such specifications must meet are given in RFC 2048(-> 4289 | 4288).
As such, all content-transfer-encoding namespace except that
beginning with "X-" is explicitly reserved to the IETF ...
... Unlike media types and subtypes, the creation of new Content-
Transfer-Encoding values is STRONGLY discouraged, as it seems likely
to hinder interoperability with little potential benefit
...
... message header, it applies to the entire body of that message. If a
Content-Transfer-Encoding header field appears as part of an entity's
...
... entity. If an entity is
of type "multipart" the Content-Transfer-Encoding is not permitted to
have any value other than "7bit", "8bit" or "binary". Even more
...
...
Certain Content-Transfer-Encoding values may only be used on certain
media types. In particular, it is EXPRESSLY FORBIDDEN to use any
...
... composite entity
has a transfer-encoding value such as "7bit", but one of the enclosed
entities has a less restrictive value such as "8bit", then either the
...
... ON ENCODING RESTRICTIONS: Though the prohibition against using
content-transfer-encodings on composite body data may seem overly
restrictive, it is necessary to prevent nested encodings ...
...
Any entity with an unrecognized Content-Transfer-Encoding must be
treated as if it has a Content-Type of "application/octet-stream ...
... CONTENT-TYPE AND CONTENT-TRANSFER-
ENCODING: It may seem that the Content-Transfer-Encoding could be
inferred from the characteristics of the media that is to be encoded,
or, at the very least, that certain Content-Transfer-Encodings ...
... Content-Transfer-Encoding could be
inferred from the characteristics of the media that is to be encoded,
or, at the very least, that certain Content-Transfer-Encodings could
be mandated for use with specific media types. There are several
...
... affect the treatment of CRLFs, given that the representation of
newlines varies greatly from system to system, and the relationship
between content-transfer-encodings and character sets. A canonical
...
... EBCDIC. A higher level of
confidence is offered by the base64 Content-Transfer-Encoding. A way
to get reasonably reliable transport through EBCDIC ...
... Base64 Content-Transfer-Encoding ...
...
The Base64 Content-Transfer-Encoding is designed to represent
arbitrary sequences of octets in a form that need not be humanly
readable. The encoding ...
... Using the MIME-Version, Content-Type, and Content-Transfer-Encoding
header fields, it is possible to include, in a standardized way,
...
... "Content-Transfer-Encoding" ":" mechanism ...