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

dialtone · on Oct 27, 2012

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.

ktsmith · on Oct 27, 2012

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.