This paper describes a template for the embedded self-description of radio equipment for use in Space Plugand-Play Avionics (SPA) systems. This template is a proposed standard that seeks to define a canonical description that might be universally applied to a variety of both simple and complex radio devices, i ncluding software-defined radios. The authors believe such t emplate approaches promote the engineering of composable systems. A template API for communications is proposed in which a great variety of differen t radios (from any conforming vendor) might be interchanged and still produce an effective mission resul t (even as a personal computer might interchange a number of approaches for connecting to the internet without re-engineering the web browser or internet applications). This common API can be used regardless of communication medium, protocols, waveforms, or operating requirements. The challenge of designing a template is in striking a balance between simplicit y in the representation of a canonical (generic) in terface that still supports the rich expressiveness needed to accommodate sophisticated radio equipment.