Re: Action 8 - Proposal for a DNT definition for 3rd Parties

Proposal is at:
https://people.mozilla.com/~tlowenthal/dnt/tpwg_action-8_proposal.md

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Interpretation of the DNT signal by 3rd Parties
===============================================

Proposal to the W3C Tracking Protection Working Group
Authored by Thomas Lowenthal, Mozilla
Associated with [Action
8](http://www.w3.org/2011/tracking-protection/track/actions/8)


When a third party receives a request where

- they know that they are a third party, and
- the DNT signal is on,

that party **must not**:

- **store** any information about that request, or
- **use** any information previously stored,
    - which can be associated with the user or device making the request,
    - in order to produce or send the response, or
- **send** any information about that request, or
    - any information previously stored about the user or device making
the request
    - to any other party, but:

- such information **may** be **stored** ephemerally, only in order to
produce and send the response to this specific request, and no longer,
- such information **may** be **stored** or **sent** if it is truly
anonymous:
    - so that it is not possible to associate such information with
either an individual or a device,
    - either directly, or in conjunction with other information or logs,
- such information **may** be **stored**, **used**, or **sent** in
connection with a specific, permitted exemption, only if
    - only as much data is stored as is needed for that exemption,
    - data is stored only as long as is needed for that exemption, and
    - data so stored is only used for the purpose of that exemption,
- these restrictions do not apply if
    - the party has affirmative knowledge that the user making the
request has opted back in to collection of data
    - by that party
    - on services operated the first party from whom the request is
referred;

that party **may**:

- **use** information plainly sent as part of that request, including
for instance:
        - the IP address of the request,
        - the referrer header of the request,
        - the time of the request,
    - when producing a response to request, but

that party **should not**:

- **use** such information plainly sent
    - to identify features of that user
    - which are not closely connected with such information plainly sent,
    - even if they can be deduced from the conjunction of such
information plainly sent and other information sources, and

that party **must not**:

- **use** any information about the user wheresoever gained
        - to serve that user a targeted advertisement,
    - except that that party **may** use information about the page from
which the request was sent
        - to serve an advertisement contextually related to the content
of that page.

(for instance:

   - that party **should not** use an IP address to estimate a ZIP code,
look up a ZIP code, or to look up the user with that IP, in order to
estimate the user's income and education level, then use that
information to select a targeted advertisement,
   - but that party **may** use an IP address to estimate a country, and
use that information to estimate which language in which to display the
page,
   - or, knowing that the request is coming from a New York Times
article regarding beaches in the Bahamas, serve a advertisement related
to holidays in the Bahamas).