14.11 Content-Base

   The Content-Base entity-header field may be used to specify the base
   URI for resolving relative URLs within the entity. This header field
   is described as Base in RFC 1808, which is expected to be revised.

          Content-Base      = "Content-Base" ":" absoluteURI

   If no Content-Base field is present, the base URI of an entity is
   defined either by its Content-Location (if that Content-Location URI
   is an absolute URI) or the URI used to initiate the request, in that



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   order of precedence. Note, however, that the base URI of the contents
   within the entity-body may be redefined within that entity-body.

14.12 Content-Encoding

   The Content-Encoding entity-header field is used as a modifier to the
   media-type. When present, its value indicates what additional content
   codings have been applied to the entity-body, and thus what decoding
   mechanisms MUST be applied in order to obtain the media-type
   referenced by the Content-Type header field. Content-Encoding is
   primarily used to allow a document to be compressed without losing
   the identity of its underlying media type.

          Content-Encoding  = "Content-Encoding" ":" 1#content-coding

   Content codings are defined in section 3.5. An example of its use is

          Content-Encoding: gzip

   The Content-Encoding is a characteristic of the entity identified by
   the Request-URI. Typically, the entity-body is stored with this
   encoding and is only decoded before rendering or analogous usage.

   If multiple encodings have been applied to an entity, the content
   codings MUST be listed in the order in which they were applied.

   Additional information about the encoding parameters MAY be provided
   by other entity-header fields not defined by this specification.

14.13 Content-Language

   The Content-Language entity-header field describes the natural
   language(s) of the intended audience for the enclosed entity. Note
   that this may not be equivalent to all the languages used within the
   entity-body.

          Content-Language  = "Content-Language" ":" 1#language-tag

   Language tags are defined in section 3.10. The primary purpose of
   Content-Language is to allow a user to identify and differentiate
   entities according to the user's own preferred language. Thus, if the
   body content is intended only for a Danish-literate audience, the
   appropriate field is

          Content-Language: da

   If no Content-Language is specified, the default is that the content
   is intended for all language audiences. This may mean that the sender



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   does not consider it to be specific to any natural language, or that
   the sender does not know for which language it is intended.

   Multiple languages MAY be listed for content that is intended for
   multiple audiences. For example, a rendition of the "Treaty of
   Waitangi," presented simultaneously in the original Maori and English
   versions, would call for

          Content-Language: mi, en

   However, just because multiple languages are present within an entity
   does not mean that it is intended for multiple linguistic audiences.
   An example would be a beginner's language primer, such as "A First
   Lesson in Latin," which is clearly intended to be used by an
   English-literate audience. In this case, the Content-Language should
   only include "en".

   Content-Language may be applied to any media type -- it is not
   limited to textual documents.