W3C home > Mailing lists > Public > public-tracking@w3.org > June 2012

Draft for breakouts - text

From: Heather West <heatherwest@google.com>
Date: Thu, 21 Jun 2012 15:02:04 -0700
Message-ID: <CA+Z3oObXr4A3__8P+=kMrhuqcaeUzMqhy8NKzuEdRFqwKJ-kRA@mail.gmail.com>
To: "public-tracking@w3.org Group WG" <public-tracking@w3.org>
3 Definitions

3.1 Parties

A party is any commercial, nonprofit, or governmental organization, a
subsidiary or unit of such an organization, or a person.

For unique corporate entities to qualify as a common party with respect to
this standard, those entities MUST be commonly owned and commonly
controlled (Affiliates) and MUST provide “easy discoverability” of
affiliate organizations.  An “Affiliate List” MUST be provided within one
click from each page or the entity owner clearly identified within one
click from each page.

For example, a clear labeled link to the Affiliate List within the privacy
policy would meet this requirement or the ownership brand clearly labeled
on the privacy policy itself.

3.2  First and Third Parties

A First Party is the party that owns the Web site or has control over the
Web site the consumer visits. A party may start out as a third party but
become a first party later on, after a user meaningfully interacts with it.

3.2.1  Service Providers/Outsourcers

Service Providers acting on the behalf of a First Party and with no
independent rights to use the First Party’s data outside of the context of
that 1st party and Permitted Uses are also considered a First Party.

It is possible to have multiple first parties on a single page but each
party must provide clear branding and a link to their respective privacy
policy (co-branded experience).

3.3 Third Party

A Third Party is any party other than a First Party, Service Provider, or a

3.4 Unidentified Data

A dataset is un-linkable when commercially reasonable steps have been taken
to de-identify data such that there is confidence that it contains
information which could not be linked to a specific user, user agent, or
device in a production environment, and which the entity will commit to
make no effort to re-identify, and prohibit downstream recipients of
un-linkable data from re-identifying it

Note: Un-linkable Data is outside of the scope of the Tracking Preference
standard as information is no longer reasonably linked to a particular
user, user agent, or device.

4 Compliance with an Expressed Tracking Preference

4.1  First Party Compliance

If a first party receives a communication to which a DNT-1 header is
attached, the first party must not [pass along/transmit/disclose]
[identifiable information about the network interaction] with [a separate
party] with which it does not have a service provider relationship.

First Parties may engage in their normal collection and use, as long as
they do not pass profile information on to third parties who could not
collect the data themselves under this recommendation.  This includes the
ability to customize the content, services, and advertising in the context
of the first party experience.

4.1.1 Service Provider to First Party

A party MUST NOT share (send or receive) collected data or profiles with
another party (unless that party is ONLY working on the behalf of that
specific party – aka Service Provider relationship).
Data collected by a 3rd party under a first party service provider
relationship MUST be segregated according to the 1st party from which it
was collected.  A 3rd party MUST NOT aggregate, correlate, or use together
data that was collected on different 1st party sites.
3rd parties MUST NOT use data across multiple, non-affiliated websites.

4.2  Third Party Compliance

If the operator of a third-party domain receives a communication to which a
DNT:1 header is attached:
that operator must not collect, share, or use information related to that
communication outside of the permitted uses as defined within this standard
and any explicitly-granted exceptions, provided in accordance with the
requirements of this standard;
that operator must not use information about previous communications in
which the operator was a third party, outside of the explicitly expressed
permitted uses as defined within this standard;
that operator may delete information about previous communications in which
the operator was a third party, outside of the explicitly expressed
permitted uses as defined within this standard.

4.3 UA


4.4 Permitted uses for Third Parties and Service Providers

For each of the Permitted Uses outlined, the following requirements apply:
Outside of Security, all other Permitted Uses will not allow for altering a
specific user’s online experience based on multi-site activity, including:
No profiling
No further alteration to the user experience based on profiled information
based on multi-site activity
Customization outside of multi-site activity profiles is allowable
Each party engaging in Permitted Uses and claiming W3C DNT compliance, MUST
provide public transparency of their data retention period
Party MAY enumerate each individually if they vary across Permitted Uses
Reasonable technical and organizational safeguards to prevent further

Examples of acceptable safeguards:  collection limitations, data siloing,
authorization restrictions, k-anonymity, unlinkability, retention time,
anonydmization, pseudonymization, and/or data encryption.

NOTE:  While definitely a Permitted Use, compliance with local laws and
public purposes, such as copyright protection and delivery of emergency
services, is not listed separately.

1. Security

Data MAY be collected and used for the express and limited purpose of
security and fraud detection and defense.  This includes data reasonably
necessary for enabling authentication/verification, detecting hostile
transactions and attacks, providing fraud prevention, or bolstering site
and system security.

Restricting security and fraud detection and defense efforts could harm
users.  We do not want to mistakenly turn Do Not Track into a signal for
user vulnerability.

Resources:  For additional details on the uses of Security data please see
the DAA Self-Regulatory Principles for Multi-site Data: Authentication,
Verification, Fraud Prevention and Security & Compliance, & Public Purpose
and Consumer Safety

2. Financial Purposes

 - Data MAY be collected and used for the limited purpose of financial
fulfillment such as billing and audit compliance.  This purpose is strictly
necessary for the continued operation of most websites and requires
uniqueness to prove user interactions (ad impression and ad click) were
indeed achieved as billed for.

3. Frequency Capping

Data MAY be collected and used for the limited purpose of frequency capping
– the practice of keeping “count” of the number of times a user or device
has seen a specific ad and then halting further display of that ad once the
designated threshold has been reached.
4. Product Debugging

Data MAY be collected and used for the limited purpose of identifying and
repairing site errors to intended functionality (“Debugging”).
5. Aggregate Reporting

Data MAY be collected and used for the express and limited purpose of
aggregate reporting.  Aggregate reporting end-points should meet the
objectives of “unlinkability” (see below) and therefore are outside of the
scope of the DNT standard.  There is a time interval necessary to retain
event level records to aggregate across the necessary time spans accurately
(daily, weekly, monthly, quarterly, etc.).


Issues to bring up separately:
Data collected and received from a party MAY be combined with existing 1st
party profile data.

Non-Normative: Unidentified

There are many valid and technically appropriate methods to de-identify or
render a data set "un-linkable".  In all cases, there should be confidence
the information is unable to be reverse engineering back to a "linkable"
state.  Many tests could be applied to help determine the confidence level
of the un-linking process.  For example, a k-anonymous test could be
leveraged to determine if the mean population resulting from a de-linking
exercise meets an appropriate threshold (a high-bar k-anonymous threshold
would be 1024).

As there are many possible tests, it is recommended that companies
publically stating W3C Tracking Preference compliance provide transparency
to their delinking process (to the extent that it will not provide
confidential details into security practices) so external experts and
auditors can assess if they feel these steps are reasonable given the risk
of a particular dataset.

Information That Is Un-linkable When Collected:  A third party may collect
non-protocol information if it is, independent of protocol information,
un-linkable data. The data may be retained and used subject to the same
limitations as protocol information.

Example: Example Advertising sets a language preference cookie that takes
on few values and is shared by many users.

Information That Is Un-linkable After Aggregation:  During the period in
which a third party may use protocol information for any purpose, it may
aggregate protocol information and un-linkable data into an un-linkable
dataset. Such a dataset may be retained indefinitely and used for any

Example: Example Advertising maintains a dataset of how many times per week
Italy-based users load an ad on Example News.

Information That Is Un-linkable After Anonymization:  At some point after
collection, a unique ID from a product cookie has a one-way salted hash
applied to the identifier to break any connection between the resulting
dataset and production identifiers.  To further remove dictionary attacks
on this method, its recommended that "keys" are rotated on a regular basis.

Non-Normative: Permitted Uses

In order to avoid DNT significantly impacting the availability of free
content on the Internet a balance is necessary to allow for minimal data
use to continue standard site operations – including those that monetize
site activities.

Non-Normative: Aggregate Reporting

While detailed event level data is not present at the outcome of aggregated
reporting it is a necessary ingredient to arrive there.

Examples of uses of aggregate reporting:
Product Improvement (via Site Analytics)
Navigation (Referring sites, Exit Points, Internal Navigation used or not
Visitor Counts (New, Returning, High Activity, Low Activity)
Market Research

the characteristics of a market or group of consumers; or
the performance of a product, service or feature, in order to improve
existing products or services or to develop new products or services.

References:  For additional examples and associated details see the DAA
Self-Regulatory Principles for Multi-site Data: Market Research & Product

Non-Normative - product debugging

Detailed information is often necessary to replicate a specific user’s
experience to understand why their particular set of variables is resulting
in a failure of expected functionality or presentation.

These variables could include items such as:
cookie IDs
URL of the page
device (UA) details
content specifics
activity/event specifics to narrow in on the cause of the discrepancy

Non-Normative: frequency capping

NOTE:  Restricting the number of times a user agent displays ads prevents a
user from having to see repetitive ads, prevents publishers from displaying
repetitive ads, and prevents advertisers from harming the reputation of
their clients.
 Examples of important data uses include, but are not limited to:
Reach and frequency metrics
Ad performance
Logging the number and type of advertisements served on a particular Web
Reference:  For additional examples and associated details please see the
DAA Self-Regulatory Principles for Multi-site Data:

Non-Normative: Financial purposes

NOTE:  Typically all relevant advertising order criteria is necessary for
retention of ad interactions.
Examples of data uses include, but are not limited to:
Ad Impression verification (CPM)
Ad Click verification (CPC)
Site Conversion associated with Ad Impression or Ad Click (CPA)
Quality Measures such as ad position (location on page, above/below fold)
and site the ad was served on (high quality vs. low quality content
Reference:  For additional examples and associated details please see the
IAB Financial Audit Guidelines.


We believe this proposal advances the existing opt-out cookie structure
(albeit that is a fair and good one) and evolves online privacy in several

Users gain a consistent, local tool to communicate their opt-out preference
Avoids property specific opt-out pages
The user's choice is persistent for each device/UA
Avoids accidental deletion
Outside of Security purposes, the user will no longer experience
alterations to their online experiences derived from multi-site activity
No profiling <aka "tracking"> and extends beyond online behavioral
Only minimal data is retained for necessary business operations and
retention periods are transparent to users
The Internet remains a viable ecosystem for free content
All real “harms” are removed
Outside of government intrusion risk where there are no documented cases of
this occurring with 3rd party anonymous log file data

We hope you agree this clearly advances the already established opt-out
program offered to users with many key new additions and evolved
perspectives to what was already a long and hard negotiated outcome for
users of the current Internet.  The online privacy debate did not begin
with the W3C Tracking Protection Working Group and most definitely won't
end with it but through collective agreement with this proposal we will
have marked an important date in the positive progression of the online
privacy debate.


Heather West | Google Policy | heatherwest@google.com | 202-643-6381
Received on Thursday, 21 June 2012 22:02:57 UTC

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