Proxies don't "understand" methods

[mnot@…]

In p6 2.5,

A cache that passes through requests with methods it does not understand SHOULD invalidate the effective request URI (Section 4.3 of [Part1]).

Poul-Henning Kamp points out that "understand" is ambiguous here.

Proposal:

A cache SHOULD invalidate the effective request URI when receiving = requests with methods other than PUT, DELETE or POST.

[mnot@…]

As PHK points out, that's not adequate for GET, etc.

New proposal:

A cache SHOULD invalidate the effective request URI when receiving requests with methods that are unsafe [ref], or whose safety is unknown.