I am using style spline to define a spline but I need to control the tangency of the spline on an axis. How do I activate the handle on a style spline to control the horizontality of the spline using a relation ?
I attach also system option screenshot for your information to show that some options related to spline are already activated.
Laurent, I don't see a problem with your option settings. Draw a construction line that is collinear to the axis you need the style spline to be tangent to and then select the spline and the new construction line and make tangent.