In classical wave mechanics, we regard space as if it was something that we actually understood that exhibits a speed of light of 300 million m/s. Within quantum-relativity, we remind ourselves that the CIPM's definition of a metre is equivalent to 3.335.. nanoseconds of quanta transit (over 3.335.. nanoseconds of clock). So, in quantum-relativity we must regard space as having units of time, and what we have called time as having units of imaginary historic depth. Therefore; the "speed-of-light" in quantum-relativity is 1/-1i, but this can be regarded is if it were +1i for most practical purposes.