What meaning does the STD 0.20 nomenclature have?

What meaning does the STD nomenclature have 0.20, 0.25, 0.5, 0.75, 1.0 ... etc. In an automotive engine?

They are piston nomenclatures, connecting rod metals and bench metals, the STD is standard the original manufacturing measure, 0.25 and the others are the envelope that is given when rectifying the crankshaft or the cylinders according to the case, this overmedy is on the factory measure, that is, 0.25 mm on the STD measurement, for example std = 92 mm, when you rectify 0.25 The measure is 92.25 mm

These nomenclatures indicate the rectification measures of the cylinders, crankshaft axis and are used to indicate the replacement values ​​of the connecting rod beans and bench as well as the pistons and segments of the same