RFC 7230, "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", June 2014Source of RFC: httpbis (app)
Errata ID: 4281
Reported By: Demian Brecht
Date Reported: 2015-02-26
Rejected by: Barry Leiba
Date Rejected: 2015-03-01
Section 3.3.2 says:
For messages that do not include a payload body, the Content-Length indicates the size of the selected representation (Section 3 of [RFC7231]).
It should say:
For outbound messages that do not include a payload body, the Content-Length indicates the size of the selected representation (Section 3 of [RFC7231]).
Assuming my interpretation is correct, this phrase as-is is a little confusing given the next paragraphs states:
"A user agent SHOULD NOT send a Content-Length header field when the request message does not contain a payload body and the method semantics do not anticipate such a body."
The former is ambiguous, the latter explicit.
The sentence in question has to be taken in context with the entire paragraph, with the rest of the section, and with the understand that it's only a summary. The details are provided in the rest of the section and in Section 3.3.3.