The IESG has concluded that this work is related to IETF work done in WG httpbis , but this relationship does not prevent publishing. The ISE and the author have agreed to add the following text in the Introduction, to address concerns from some ADs about clarity of the document's history and that it's not a standard: --------------------------------------------------- The mechanism described in this document does not have IETF consensus and is not a standard. It is a widely deployed approach that has turned out to be useful, and is presented here so that server and browser implementations can have a common understanding of how it operates. This mechanism was presented for publication as an IETF Proposed Standard, but was not approved for publication by the IESG despite having IETF consensus at that time. Concerns raised by the IESG included the vagueness of the meaning of "safe", the ability of a proxy to insert the hint outside of a user's control, and the fact that there is no way to know whether the hint was or was not applied to the response returned by the server. While the current text is clear about these issues, they remain as factors that block the IESG's approval of this mechanism as an IETF Proposed Standard. ---------------------------------------------------