People will call it a notch if they don't know the purpose . It is called a lock because it locks the bearing and prevents it from spinning in the bore. A notch is cut into a surface the bearing lock is stamped in.
The notch would be in the bearing bore to accept the lock that is stamped in the bearing.
It is actually called a "TANG". It only locates the bearing, and has nothing to do with preventing rotation. The "crush" of the bearing in the housing bore prevents rotation.
