the opturi

In the p3p policy, is it permissible to specify more than one opturi for a purpose?

Example, the <individual-analysis> purpose. A site has a registration service that uses a cookie, and that information is tied to a specific user account, and the site analyzes that data. The opt-in would be the sign up for the service, when the user creates an account. But, what if the sign up can be done, for the same service, in more than one place on the site - should more than one opturi be specified, or is one sufficient, or should these be broken into more than one purpose, ... 

Thanks.