Most popular variants of the header value (we only show this when there's just a bunch of variants):

Do-Not-Track (DNT) header can be seen in both in HTTP request and response. In the request, it indicates the user's preference as it comes to online tracking and behavioral advertising (1=don't mind tracking, 0=do not track). In response, a compliant server should respond with the same value. In addition, Tk (Tracking Status) header should be set.detailing the tracking policy.

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