These components take an existing spline as input and produce a new, altered spline. In many procedural content creation software this input Spline is called the “control spline”.

Any one of them can be added to a Spline Container through the dropdown menu:

They will have this Trigger Event dropdown. It determines when the component should execute its behavior.

You may want to opt to choose “After Spline Changes”, so that a component only executes once the Source spline has finished being altered. Rather than constantly.

When choosing the “During Spline Changes” option, changes will be visible immediately, but Editor performance may degrade, as a Spline could be changed many times within a few milliseconds.

If it is set to “None”, a button will appear to trigger an update manually.