One could just as easily argue that a user should only be tracked if it's their explicit intent to be tracked, in which case DNT should be on unless the user turns it off. That makes more sense to me, and I think a lot of people would agree. Obviously, Microsoft thinks that should be the case.

I have a hard time believing MS is doing this for their users benefit. It seems much more likely they think this will hurt Google.

Next you'll tell me corporations mainly donate to charity for tax purposes and free publicity...

I don't care if they're really doing it to hurt Google. Increased privacy for users is a good thing.

You can waffle all you want about user intent, but it's quite obvious that they will only support an opt-out scheme.

Advertising almost never implement opt-in unless legally forced to.

What method are they using to determine if it's _actually_ the user's intent?

You have to explicitly set it on, that means the user had to take a specific action, and that means there was an intent to do it.

There are three values that the header can contain.

  null - no value set
  
  0 - opted in to tracking
  
  1 - opted out of tracking

A 0 or 1 imply intent and null would imply the user has taken no action.