Engineers programming automated optical inspection or coordinate measuring machines (CMM) cannot hard-code tolerance limits. They must program a decision rule. The formulas in the official guide allow for real-time risk-based decision-making.
The most authoritative source is the (www.iso.org). iso iec guide 98-4 pdf
However, a critical gap remained. While Part 3 (the GUM) explained how to quantify uncertainty, it did not explain how to use that uncertainty in making decisions about conformity. Is a component within tolerance? Is a pharmaceutical batch safe? Without a bridge between measurement uncertainty and decision rules, industries faced significant risks of false acceptance or false rejection. iso iec guide 98-4 pdf