picking a new AF_* number for NETLINK ?

In porting the kernel openvswitch code to FreeBSD we
have implemented netlink sockets, so we need to pick a
number to use for AF_NETLINK/PF_NETLINK in the messages.

Obviously we'd like ovs to be loadable as a module on existing
kernels, so i wonder if there are any restrictions on what we
can use -- specifically, whether we should make sure that

	AF_NETLINK < AF_MAX 

or that is irrelevant.

cheers
luigi