Reduced level

Reduced level is a way to measure how high or low something is compared to a reference point. Imagine you are playing a game where you have to stack blocks of different sizes on the floor. One of the blocks is your reference point, the one you start with. Let's say you put it on the floor and you call it level zero. Now, you want to stack another block on top of it. You measure the height of this new block from the floor to the top and you find out it is one centimeter high. You then add this height to the height of the reference point and you get one centimeter as the new reduced level. If you stack another block on top of the second one and measure its height, you add that height to the previous reduced level and you get a new reduced level. Essentially, reduced level is a way to keep track of how high or low something is relative to a starting point.