Code change:
that implementations advertising only HTTP/1.0 support will not understand how to process a transfer-encoded payload.  A client MUST NOT send a request containing Transfer-Encoding unless it knows the <del> server will handle HTTP/1.1 (or later) requests; such knowledge might be in the form of specific user configuration or by remembering the version of a prior received response.  A server MUST NOT send a response containing Transfer-Encoding unless the corresponding request indicates HTTP/1.1 (or later). </del> <ins> server will handle HTTP/1.1 requests (or later minor revisions); such knowledge might be in the form of specific user configuration or by remembering the version of a prior received response.  A server MUST NOT send a response containing Transfer-Encoding unless the corresponding request indicates HTTP/1.1 (or later minor revisions). </ins> A server that receives a request message with a transfer coding it does not understand SHOULD respond with

Related discussion:
text: NAME the ABNF is not the source of truth; as discussed, it's the recommended generated form. We have prose in that we use to do things like explicitly allow LFs to be separators and folding to be performed. Given that there is confusion, interoperability issues and security issues around bare CRs, a clear requirement seems proportional - especially when the ABNF does not specify error handling. I could see an argument to downgrade the requirement relating to generation to a note that it's not allowed, and I could see broadening the language in semantics to say that CRLF and LF are also not allowed.
For field values (Semantics), we clarify that these are illegal to generate. For recipients, we can say that for error handling, rejecting or converting to SP is common. Not sure what else needs to be said in Messaging.
I think that the security aspect justifies a new requirement; how about "MUST either reject or remove; suggest replacing with SP"? I was thinking about outside the field values -- mostly in the request-line and status-line. That said, I agree it's much less of a concern there, and I'm OK with dropping it if you think it's not worth it. I'll update the PR if you think the above is workable.
s/MUST either reject or remove/MUST either reject or replace/ ...I guess. Yes, that sounds right to me; although there might be pusback on the MUST (me neutral). The part for Messaging I believe deserves a separate issue and discussion.
NAME I'll make a change note in Messaging. WRT Semantics, the adjacent text about folding effectively deals with LF and CRLF. If you want to go to the trouble of separating into two issues and two pull requests, feel free. I'd rather just get it closed.
/me looks - NAME it already is called out. Please re-review.
On my agenda for today.
opened for field values
Splitting the issue was king of intrusive, sorry for that. The changes for [Messaging] have been merged. For [Semantics] please see URL
Popular clients handle LF, CR, and CRLF as newlines. HTTP only defines CRLF. Previously: URL
To clarify, this is about the CRLF in the HTTP-message production.
Covered here: URL ... but I agree it could be more visible (e.g., in 3).