RE: i37: Vary and non-existant headers

Yves Lafon wrote:
> How about:
> "Implementations might define header matching as the equivalence of
> their internal representations".

That looks like "Header matching is implementation-defined."

It makes sense that transparent proxies must use character-by-character
comparison (no canonicalization). Non-transparent proxies are already free
to rewrite the "Accept-Encoding" header of requests, so they are free to do
whatever canonicalization they want (RFC 2616 section 13.5.2), AFAICT. That
is, a proxy cache that treats "Accept-Encoding: inflate, identity" the same
as "Accept-Encoding: inflate" is the same as a non-transparent proxy cache
that rewrites "Accept-Encoding: inflate, identity" to "Accept-Encoding:
inflate". Such a cache can't claim to be transparent (because it isn't).

- Brian