Making the axis of the bubble tube perpendicular to vertical axis of the level is
ATemporary adjustment of Dumpy level
BRefraction correction of Dumpy level
CPermanent adjust of Dumpy level
DCurvature correction of Dumpy level
ATemporary adjustment of Dumpy level
BRefraction correction of Dumpy level
CPermanent adjust of Dumpy level
DCurvature correction of Dumpy level
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