I'm just payng with SPLINES and it is something interesting. Example:
PTP_SPLINE
SPTP XP1
SPTP XP3
SPTP XP2
ENDSPLINE
But I had to touch up the points fist using the inline form then put those points out of my loop and use them into SPLINE movements. How it is possible to touch up those pints? or you have to declare it and manually fill the respective coordinates...