Waves are described in terms of their height, wave-length, and period. “Height” is the vertical distance between the high point of a wave crest and the low point of the adjacent trough. “Wave-length” is the distance from one crest to the next, and “period” is the time it takes two adjacent crests to pass a fixed point, such as the end of a pier. The mathematics of wave theories are usually concerned with relationships between these and related characteristics.
The various armed forces adopted all of those aspects in 1976. At that point in time, the test was in its written form rather than today’s more common form (computerized test format). The written form covers all of the previously mentioned areas as well, which is why both forms are still available. All-in-all that answers the question concerning the intention of the test.