norm pre-defined method(s)

There is a method called “norm” defined in structs position3d, velocity3d, and acceleration3d. I tried looking for information about this method, but I haven’t been able to find any in the LRM.

Based on my intuition, I guess it refers to the normalized value of position, velocity, etc wherein we are supposed to calculate the unit vector, is that right? If not, what exactly is the purpose of these methods?