header('P3P:CP="IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT"');

http://gromitski.com/blog/using-cookies-in-a-facebook-application/

Compact Privacy Policy allowing cookies to be used in an iframe without being blocked by the host website. See link for further details.

Getting 3rd party cookies to work in an iframe

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