Use this procedure to hide or show the boundary of a break mark that masks an underlying object. A masking break mark is defined by an AEC polygon style and a polyline.
Note: To see these options you must select the AEC polygon, not the polyline (which defines the cut line).
- Select the break mark.
If you want to… Then… show an edge click 
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The boundary edge of the break mark (represented by the AEC polygon) highlights. Select the edge to show, and press Enter.
hide an edge click
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The boundary edge of the break mark (represented by the AEC polygon) highlights. Select the edge to hide, and press Enter.
Since the masking behavior of a break mark depends on an AEC polygon, many of the same editing options available for AEC polygons can also be applied to masking break marks.