This Recommendation describes requirements for using formal methods. Formal methods are mathematics-based techniques used to specify@ develop and verify software and hardware systems in the context of software-defined networking (SDN) for future networks (FN). The scope of this Recommendation covers: an overview of formal methods (formal specification and formal verification) for SDN@ and requirements for applying formal methods to SDN. An example of how to apply formal methods to SDN is provided in Appendix I.