Can someone explain how landclass, mesh, textures, and add-ons like USARoads work together. Which programs do what to the FlightSim experience? I have been flying for quite a while, but only with add-on aircraft and a few detailed cities. It would be nice to know how these things work, what they do, and what can be changed (in a city: move/modify a structure that is not in the right place). Also, how are these placed in the scenery list so they work correctly, and do not conflict.