Professionally it is a branch of industrial design, similar to automotive design using identical techniques and methodology, but confined by a set of conventions about what is acceptable to the buying public. These conventions have been defined by the acceptance of the industry and media as a whole to the assumption that the public will only purchase machines that bear more than a passing resemblance to competition machines of whatever kind. In some large OEM motorcycle manufacturers, the term designer can also be applied to the project leader or chief engineer charged with laying down the principal architecture of the vehicle. In recent years it has also become associated with custom or "chopper" builder culture.