The "LIST", is simply the names of "approved" airplanes for SPA competition. There are lots of choices. It is expected that these airplanes conform to original design specs in terms of basic measurements, ie. wingspan, fuselage length, wing area, and external shape. What's inside in terms of construction technique, radio equipment, or materials is not at issue. Fixed landing gear (or retracts if the gear remains extended) is required but may be tricycle or tail dragger as the builder prefers. No tuned pipes. Engine or motor standards are specified. That's pretty much it. Four classes of very stiff competition. Lot's of fun. Excellent fellowship. Nobody runs around with a tape measure. It's pretty much an "honor" system.