Open Stack

Over the holidays I realized there's something about the proposed Neutron policy API that I don't understand.  Is the proposed API complementary to the core API, or is it intended to be an alternative?  By complementary, I mean that a user can create a bunch of networks, subnets, and ports and then constrain how those things interoperate by writing policy.  By an alternative, I mean that a user must choose either networks/subnets/ports or policy, but cannot choose both.  I had always assumed we were talking about a complementary API but wanted to double-check.

Thanks,
Tim