Snaps to one of the division points of an arc or line segment. 
The default number of segments is 3, but you can change this in the Segments field of the Drawing Aids window. Open this window by right-clicking on the SNAP or GEO button next to the Coordinate Fields. 
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Tip: You can also divide arcs and line segments while using the Edit Tool, by selecting Divide Segment or Arc Divide from the local menu. See Edit Tool
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