P3P and cross-domain cookie Access (read and set)

In IE, cross-origin is used to set cookie cross-origin implementation. I tried n Chinese methods. I checked the information and can implement it by setting the p3p value in the header. It's really good :)
For example, to access site B and set a cookie on Site a, you can do this:
1. Create a cookies.htm file under B .com.
Content:

1 <script language = "javascript" src = "http://a.com/setcookies.asp? Par = a.com "> </script>

The content of setcookies. asp under 2.a.com is:

<%
Response. AddHeader "P3P", "CP = CURa ADMa DEVa PSAo PSDo our bus uni pur int dem sta pre com nav otc noi dsp cor"
Response. Cookies ("aaa"). Domain = Request ("par ")
Response. Cookies ("aaa") = "this is the cookie set by accessing files under a.com under B .com"
%>

In this example, the cookies.htm file under mongob.comcan be used to set and modify the corresponding cookies under the.com domain, so as to achieve the purpose of cross-origin access cookie setting.