Does P3P specify a common policy for opt-out?
The P3P specificatiion does not directly address opt-out. We do have a change_preferences field in our public working draft. In general, many companies offer individuals an opportunity to opt-out of certain types of uses of their data. For example, a company may allow you to opt-out of having your name included on their mailing list. Whether your name is actually erased entirely from their database depends on the company. If you are a customer, they will probably keep your name so that they have a record of whatever transactions you have done with them. You may find additional information about opt out on the Online Privacy Alliance web site at http://www.privacyalliance.
