Why we write it down
Laban, the kinesphere, and what the site derives from them.
The vocabulary already existed
Rudolf Laban spent the first half of the twentieth century building a way to write movement down. Two parts of it are used here. The kinesphere is the space a body can reach without travelling, modelled as an icosahedron — twelve points, and the twelve fall into three golden rectangles at right angles, which is a property of the solid rather than a convention somebody agreed to.
The other part is Effort: four factors, each running between two named ends. Weight from light to strong, time from sustained to sudden, space from indirect to direct, flow from free to bound.
What the site does with it
Every piece stores a path — a sequence of the twelve — and a position on the four factors. From those the site works out the Basic Effort Action from Laban’s own table, which plane the phrase mostly lives in, and how far the body travels measured in kinesphere radii. Nothing is typed twice and no adjective is stored anywhere.
When it says it does not know
Three of the four factors decide the action name, and a piece scored near the middle of any of them is genuinely between two actions. The site reports a low certainty and says so instead of rounding to the nearest word. The Table Is Level is the clearest case in the repertoire.