High Quality Content by WIKIPEDIA articles! A straightedge is a tool with an accurately straight edge used for drawing or cutting straight lines, or checking the straightness of lines. If it has equally spaced markings along its length it is usually called a ruler. True straightness can in some cases be checked by using a laser line level as an optical straightedge: it can illuminate an accurately straight line on a flat surface such as the edge of a plank or shelf.

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