公差 (gōng chā) is a technical term from engineering and manufacturing meaning 'tolerance' — the allowable deviation from a specified dimension or measurement. However, the same characters are also read gōng chāi, meaning 'public errand' or, historically, a yamen runner (bailiff). This row's pinyin (gōng chā) points to the tolerance sense, while the English gloss describes the errand sense — a mismatch that needs human correction. For the tolerance meaning, it appears in contexts like 尺寸公差 ('dimensional tolerance') and 配合公差 ('fit tolerance').