In order to give instruction towards the instrument rating, multi rating, type ratings, and class conversions (for example, land plane to sea plane), an instructor rating is not necessarily required. The requirements may be limited to holding a commercial or airline transport license and having met certain experience levels (such as time on type and in class). In the case of an instrument rating, the holder of a flight instructor rating can teach it even if they do not have the experience level required for non-flight instructors. Details are contained in the "Canadian Aviation Regulations", parts 401 and 421.