Ipo ... getRctf() ??? What's that?

The Dokumentation says, it’s a Kind of Bounding Box of the Ipo Curves. But the Values i get with this do not match to max and min Dimensions of the Ipo. Can someone explain me how this works, please?
Thanks, Doc

The bounding box of an IPO curve. This rtcf() is an internal variable and this should probably be deprecated.