The manufacturers’ Farm and Industrial Equipment Institute (FIEI), which wrote the first ASAE standards dealing with rollover protection (Standard R-305.1 and R-306), in 1967 required that roll bars be a standard item on new tractors. Standard R-305.1 dated 1967 states that tractors “shall” be equipped with a protective frame meeting the rollover protective frame requirements of ASAE Standard R-306. Standard R-305.1 was a recommended standard of the ASAE. It subsequently was adopted as an official standard in February of 1970. It wasn’t until 1972 that the ASAE, realizing what they had done, changed their standard to make roll bar installation on tractors optional--at least as to those manufacturers who chose to follow the voluntary ASAE standard. In 1985, they finally changed the standard to require roll bars on all new tractors as it had been from 1967 to 1972.