Use this feature to toggle activation of the Chain Filter feature when using a Chain selection or pre-selecting. Border indicates active state. While using a chain operation and Chain Filter is active you can temparily toggle off using the space bar.

The chain filter operation is dictated by the cursor position when hovering over entities and choosing the start position for the chain ( End Point, Mid-point, Center for example). This will influence both direction and included geometry for the chain. The chan filter will operate on any open profile, for closed profiles choose the Profile Filter function.  Below are a few illustrations of this behavior:

Line string chain selection result based on selection positioning:

NOTE: Line string made in 3D, 1-5 lines left to right =Cplane 1, line 6 right vertical = Cplane 2. CPln Q = off. This example uses Transform>Delta>Copy

 

Above with CPln Q = On