Re: action-231, issue-153 requirements on other software that sets DNT headers

Thanks Vinay, this is very helpful---I had been wrestling with some of these possibilities in my head, but it's useful to see the scenarios spelled out.

Sent via mobile, please excuse curtness and typos

-----Original message-----
From: Vinay Goel <vigoel@adobe.com>
To: Justin Brookman <jbrookman@cdt.org>, "public-tracking@w3.org" <public-tracking@w3.org>
Sent: Thu, Aug 23, 2012 04:25:04 GMT+00:00
Subject: Re: action-231, issue-153 requirements on other software that sets   DNT  headers

Hi Justin,

You bring up an excellent point that I've been struggling with myself — on whether a response header to the UA saying 'I refuse to honor this header' is enough.  The problem I'm struggling with is that I don't see a practical way websites can provide more notice in a consistent manner that's helpful to consumers.  I believe the UA could via making available the results of the response header, but that’s a whole-nother discussion.

Here is an example that will hopefully illustrate the challenge.  I believe the site notice paradigm breaks down in at least a few situations: a) where the third party has no direct communication with the consumer, thus being dependent on the website/publisher; and b) when there are multiple third parties on the same page, and the third parties treat headers via IE10 differently.  If we are hoping for quick and widespread adoption, we have to make it relatively easy for the websites to adopt without placing significant challenges/notice requirements.  Note: I am making an assumption that ad firms will be implementing DNT as an all-or-nothing thing; meaning if and how they honor DNT will be for all clients; it will not be managed at a per-client level.  {If ad networks are approaching this in a different manner, please let me know}

Background:
- Both Foo Marketing Co and Bar Marketing Co are site retargeting firms.  Neither company has a consumer-recognizable brand, yet both companies are highly regarded with