14.40 Trailer
The Trailer general field value indicates that the given set of header fields is present in the trailer of a message encoded with chunked transfer-coding.
Trailer = "Trailer" ":" 1#field-name
An HTTP/1.1 message SHOULD include a Trailer header field in a message using chunked transfer-coding with a non-empty trailer. Doing so allows the recipient to know which header fields to expect in the trailer.
If no Trailer header field is present, the trailer SHOULD NOT include any header fields. See section 3.6.1 for restrictions on the use of trailer fields in a "chunked" transfer-coding.
Message header fields listed in the Trailer header field MUST NOT include the following header fields:
. Transfer-Encoding
. Content-Length
. Trailer