Network Working Group R. Fielding Request for Comments: 2616 ...

Message headers listed in the Connection header MUST NOT includeend-to-end headers, such as Cache-Control.HTTP/1.1 defines the "close" connection option for the sender tosignal that the connection will be closed after completion of theresponse. For example,Connection: closein either the request or the response header fields indicates thatthe connection SHOULD NOT be considered `persistent' (section 8.1)after the current request/response is complete.HTTP/1.1 applications that do not support persistent connections MUSTinclude the "close" connection option in every message.A system receiving an HTTP/1.0 (or lower-version) message thatincludes a Connection header MUST, for each connection-token in thisfield, remove and ignore any header field(s) from the message withthe same name as the connection-token. This protects against mistakenforwarding of such header fields by pre-HTTP/1.1 proxies. See section19.6.2.Fielding, et al. Standards Track [Page 117]RFC 2616 HTTP/1.1 June 199914.11 Content-EncodingThe Content-Encoding entity-header field is used as a modifier to themedia-type. When present, its value indicates what additional contentcodings have been applied to the entity-body, and thus what decodingmechanisms must be applied in order to obtain the media-typereferenced by the Content-Type header field. Content-Encoding isprimarily used to allow a document to be compressed without losingthe identity of its underlying media type.Content-Encoding = "Content-Encoding" ":" 1#content-codingContent codings are defined in section 3.5. An example of its use isContent-Encoding: gzipThe content-coding is a characteristic of the entity identified bythe Request-URI. Typically, the entity-body is stored with thisencoding and is only decoded before rendering or analogous usage.However, a non-transparent proxy MAY modify the content-coding if the