Here is how it looks:
"Control Cage
At first sight this curve type looks very much like the Custom curve, but there are some differences. With the Custom curve, the curve touches all the control points. This is not the case with the control cage curve – the control points attract the curve towards them but the curve doesn’t actually go through them. Another difference is that the control cage allows for a straight section of the curve, while you can't do this with the custom curve. The cage curve needs at least three points for that (so five in total). Holding down the Shift key while dragging a point will help you to easily create a straight line by snapping the point to the line made by the previous and next point (displayed in red by the 'snap to' tool). Many users prefer Control Cage type curves to the alternatives."
Also only "Control Cage" or "B-spline" curves mode combined with snapping points to cage could provide perfect curve to adjust Exposure + highlights compression (discussed earlier here https://www.pl32.com/forum3/viewtopic.php?t=7075):
