interoperability between clients and servers, specifications of the
   content coding algorithms needed to implement a new value SHOULD be
   publicly available and adequate for independent implementation, and
   conform to the purpose of content coding defined in this section.

3.6 Transfer Codings

   Transfer-coding values are used to indicate an encoding
   transformation that has been, can be, or may need to be applied to an
   entity-body in order to ensure "safe transport" through the network.
   This differs from a content coding in that the transfer-coding is a
   property of the message, not of the original entity.

       transfer-coding         = "chunked" | transfer-extension
       transfer-extension      = token *( ";" parameter )

   Parameters are in  the form of attribute/value pairs.

       parameter               = attribute "=" value
       attribute               = token
       value                   = token | quoted-string

   All transfer-coding values are case-insensitive. HTTP/1.1 uses
   transfer-coding values in the TE header field (section 14.39) and in
   the Transfer-Encoding header field (section 14.41).

   Whenever a transfer-coding is applied to a message-body, the set of
   transfer-codings MUST include "chunked", unless the message is
   terminated by closing the connection. When the "chunked" transfer-
   coding is used, it MUST be the last transfer-coding applied to the
   message-body. The "chunked" transfer-coding MUST NOT be applied more
   than once to a message-body. These rules allow the recipient to
   determine the transfer-length of the message (section 4.4).

   Transfer-codings are analogous to the Content-Transfer-Encoding
   values of MIME [7], which were designed to enable safe transport of
   binary data over a 7-bit transport service. However, safe transport
   has a different focus for an 8bit-clean transfer protocol. In HTTP,
   the only unsafe characteristic of message-bodies is the difficulty in
   determining the exact body length (section 7.2.2), or the desire to
   encrypt data over a shared transport.




 
RFC 2616                        HTTP/1.1                       June 1999


   The Internet Assigned Numbers Authority (IANA) acts as a registry for
   transfer-coding value tokens. Initially, the registry contains the
   following tokens: "chunked" (section 3.6.1), "identity" (section
   3.6.2), "gzip" (section 3.5), "compress" (section 3.5), and "deflate"
   (section 3.5).

   New transfer-coding value tokens SHOULD be registered in the same way
   as new content-coding value tokens (section 3.5).

   A server which receives an entity-body with a transfer-coding it does
   not understand SHOULD return 501 (Unimplemented), and close the
   connection. A server MUST NOT send transfer-codings to an HTTP/1.0
   client.

3.6.1 Chunked Transfer Coding

   The chunked encoding modifies the body of a message in order to
   transfer it as a series of chunks, each with its own size indicator,
   followed by an OPTIONAL trailer containing entity-header fields. This
   allows dynamically produced content to be transferred along with the
   information necessary for the recipient to verify that it has
   received the full message.

       Chunked-Body   = *chunk
                        last-chunk
                        trailer
                        CRLF

       chunk          = chunk-size [ chunk-extension ] CRLF
                        chunk-data CRLF
       chunk-size     = 1*HEX
       last-chunk     = 1*("0") [ chunk-extension ] CRLF

       chunk-extension= *( ";" chunk-ext-name [ "=" chunk-ext-val ] )
       chunk-ext-name = token
       chunk-ext-val  = token | quoted-string
       chunk-data     = chunk-size(OCTET)
       trailer        = *(entity-header CRLF)

   The chunk-size field is a string of hex digits indicating the size of
   the chunk. The chunked encoding is ended by any chunk whose size is
   zero, followed by the trailer, which is terminated by an empty line.

   The trailer allows the sender to include additional HTTP header
   fields at the end of the message. The Trailer header field can be
   used to indicate which header fields are included in a trailer (see
   section 14.40).