Open spline

You can add an open curve by clicking four points, at least.

When adding a line, you can use an auxiliary function to mirror a line being drawn automatically. You can use ruler functions, when clicking points of a line.

1. Select Lines> Open Spline.
2. Select line properties.
3. Indicate the spline points; at least four points.
4. Select Confirm.

Line Properties
Automatic Mirroring of a Line
Ruler Functions