All approved sims have an authority code (often referred to by another name but I can't remember what). All FTOs using approved sims (lowly and sophisticated) have an approval certificate from the CAA specifying this code. One of the Stapleford training organisations displays these certificates on the wall - good idea I think because from personal experience, FTOs don't always have the info to hand and it's something I always include in my logbook to show that I was using a "proper" sim.