Importance of selection points in the Entities mode of Trim/Extend Curves with Limits

In the Trim/Extend Curves with Limits command, when the Boundaries mode is set to Entities, in case of multiple intersections between the boundaries and the curve to be modified, the results you will obtain depend on the positions at which you click to select them:

• The actual intersection point that will be taken into account is the one closest to the selection point of the boundary.
• The selection point of the curve defines the part of it that will be retained (that is: not removed or extended).

See the following example, where you have two intersections between the boundary and the curve to trim:



First you select the boundary curve, close to the intersection on the left:



Then you select the curve, as displayed in the illustration:



The part of the curve that will be retained is the one identified by the selection point of the curve itself, while the intersection point actually used by the command is the one close to the selection point of the boundary. The part of the curve beyond that point will be removed.



In the following example you can see the same behavior in the case of extension.



First you select the boundary curve, close to the intersection with the lower end point of the curve to modify:



Then you select the curve, as displayed in the illustration:



The part of the curve that will remain unchanged is the one identified by the selection point of the curve itself, while the intersection point actually used by the command is the one close to the selection point of the boundary. The part of the curve beyond that point will be extended.