A small display increment is mistaken for acceptance

A fictional shaft drawing specifies a permitted diameter interval, while a digital instrument displays small increments. A trainee obtains a repeatable reading close to the nominal value and declares the shaft acceptable without checking the instrument’s actual accuracy, calibration, temperature conditions or the allowed interval. A colleague distinguishes the nominal dimension, tolerance and measurement uncertainty. This written exercise accepts no physical part and performs no assembly. It asks why a fine display and repeated values do not independently establish correct size, which supplied records matter for acceptance and how a controlled comparison can preserve the distinction between a convenient reading and justified conformance to the actual specification.