InternetSetCookieEx with the INTERNET_COOKIE_EVALUATE_P3P flag

Hi, I'm trying to set a cookie using INTERNET_COOKIE_EVALUATE_P3P with
the reserved string.
I can't find any doc on either of these, and the format for the p3p
string that follows. Nothing can be found on msdn, or anywhere else I
looked.
whatever the string used like "CP=CAO PSA OUR" I always get the same
response, COOKIE_STATE_LEASH. meaning that the cookie is only set to
the first party

if anyone already tried this, just can't wait to hear from you, thx