This is a common term used by the industrial and commercial system when approving business licenses. It just gives you a general range. Wujinjiaodian generally refers to some small household appliances, door locks, etc.; electromechanical equipment refers to some civil or household electric drills, electric saws, motors, etc.; building materials refers to materials used in civil construction, such as bricks, tiles, cement , insulation materials, etc. You can operate whatever you think fits your business scope.