character set
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... open-ended framework and can accommodate additional object types,
character sets, and access methods without any changes to the basic
protocol. A registration process ...
... things that are better thought of as a transfer encoding, as a
character set, or as a collection of separate entities of another
type, is not allowed. For example, although applications exist to
decode the base64 ...
... Media types must function as an actual media format.
In particular, character sets and transfer encodings
may not be registered as media types ...