With two weeks left until its own latest deadline to agree on "Do Not Track" standards for web browsers, a Worldwide Web Consortium working group has been thrown for a loop by a new proposal from its ad industry members.

The proposal would alter the way analytics firms, marketers and others that track web surfers would have to react when they encounter a Do Not Track signal, letting them continue collecting and using behavioral data. In exchange, the industry would agree to strip that data of certain information it may keep otherwise.

If a user with Do Not Track enabled visits Cars.com, for example, the proposal would let third parties peg him as interested in cars but not as a visitor to that particular site. Stricter Do Not Track standards being considered would let Cars.com tag visitors to its own site but prevent third parties from dropping cookies on those visitors.

The proposal was submitted by the Interactive Advertising Bureau, the Digital Advertising Alliance, the American Association of Advertising Agencies, the Association of National Advertisers, the Network Advertising Initiative and others. They are particularly perturbed by what they say is a steady increase in Do Not Track signals sent without explicit user consent, from security and privacy software as well as browsers like Microsoft's Internet Explorer 10, which makes Do No Track the default instead of requiring users to activate it.

"The DNT flag has been hijacked," said Mike Zaneis, senior VP and general counsel of the Interactive Advertising Bureau, using the industry shorthand for Do Not Track. "It is flawed as a tool for reflecting consumer choice because it is an open tool that anyone can manipulate. Let's not play this game of charades and pretend this is a consumer signal -- it's not."

While he couldn't provide hard numbers, Mr. Zaneis said publishers in the IAB have seen the amount of DNT signals "creeping up" to around 20% of their visitors. "We realized it was because anybody could send a DNT flag," he said.

It isn't clear how the ad industry proposal is much different from current behavioral tracking and targeting practices. Categorizing people into audience segments is what third party behavioral ad systems already do; the main difference in the industry proposal is that actual domains visited by those categorized users would not be stored.

A "higher level of data hygiene" would be afforded to people with Do Not Track enabled, said Mr. Zaneis.

Multiple delays
The proposal has already encountered resistance. "We object on both content and process grounds," said David Singer, a software standards exec at Apple and member of the Worldwide Web Consortium group developing the Do Not Track standard, in a public comment on the proposal. "We do not believe that the major changes to de-identification and the definition of tracking are either an improvement or sufficiently precise to be watertight."

For more than two years the Worldwide Web Consortium, also known as the W3C, has been publicly debating technical and policy aspects of a Do Not Track standard. The project deadline has been postponed multiple times amid internal squabbles. Though some working on the W3C's Do Not Track initiative believe consensus can be reached, others do not, the most vocal of whom has been Stanford privacy activist Jonathan Mayer.

"Our Last Call deadline is July 2013," Mr. Mayer wrote on the public W3C site in June. "That due date was initially January 2012. Then April 2012. Then June 2012. Then October 2012. We are 18 months behind schedule, with no end in sight. There must come a time when we agree to disagree. If we cannot reach consensus by [July], I believe we will have arrived at that time."

"Unless the procedure suddenly shifts… then we just keep arguing over the same old stuff," Mr. Mayer said in an interview.