石工 normally refers to a stonemason or masonry work and is pronounced shígōng. However, the pinyin dàn corresponds to a different reading—possibly an old variant or a specialized term (e.g., a unit of capacity, 石=dàn). The row's gloss 'masonry; stonemason' contradicts the given pinyin dàn, which is never used for that meaning. This looks like a data error.