Explanatory notes
… bubble type, etc.) used in building or constructional work (e.g., by masons, carpenters or mechanics), and plumb‑lines ( … etc., maps, but they are also used for other purposes (e.g., study of tides, ground‑swells, etc.). The maps, etc., … instruments described in paragraphs (IV) (1) and (2) above (e.g., liquid level indicators, flow meters, etc.) are, …