PF NAT Rules

[Daniel Corbe]

Is there a way to express the following in a PF rule or a set of PF rules?

"NAT from 10.64.14.0/24 to any unless I have a route in my routing table 
to the destination"

The reason I want to do this is because I have OSPF running on my 
firewall box.  And it exchanges routing information and learns external 
routes that I don't necessarily want natted.

Regards,
DAniel