Redirect chains and DNT:0 / Exception:* (ACTION-146 re ISSUE-111)

Upon reflection, this is probably just further discussion for ISSUE-111. I
also can't seem to find the canonical text that ISSUE-111 is proposing.
That said, my understanding of the proposal is essentially allowing for
negotiation of (on this site, X can track me) where X is a single third
party, list of third parties, or all third parties.

My main concern is that, as a website author, you may include ads from a
given ad network (be that doubleclick, yieldmanager, adecn, or whatever)
but have no idea what other third parties those ad networks syndicate to.
You want higher quality ads on your site (which presumably translates to
more revenue for the site), so you request an exception for the third party
ad network you use directly. But, you have no idea, in the presence of
syndication, what the final ad provider will be, so you have no way of
requesting an exception.

It seems like the only meaningful thing is to request *, at which point I
wonder why we're making this so complicated, rather than just two options
-- "I request an exception for myself" vs "I request an exception for
myself and third parties on my page."

-Ian