Since the early 1980s, the FIA requires that Formula One entrants own the intellectual rights to the chassis that they enter. Basically, that means that teams must build their own chassis. Since this time, the terms "entrant", "constructor", and "team" now mean the same thing. Before this time, constructors were free to sell their chassis to other teams. Brabham and Lotus chassis were used by many other teams during the 1960s and 1970s. Several teams than compeated with the front-runners never built their own chassis. Rob Walker Racing Team was the most successful example. They earned the first victories in Formula One for both Cooper and Lotus. 