Iso 8015 _best_ -

The standard also birthed the modern era of . Before ISO 8015, a CMM operator had to guess the datum scheme. After ISO 8015, the drawing explicitly told them: "Measure from datum A (the bottom face), then datum B (the left edge), then datum C (the back stop)." The machine could now be programmed with absolute certainty.

If a designer wants the size tolerance to act as an envelope (ensuring the shaft fits inside a perfect theoretical cylinder), they must explicitly indicate this by adding the symbol (Envelope requirement) to the drawing. iso 8015