ICEMsurf uses Bezier math to construct surface patches and curves. The benefit of Bezier math is that patches are smooth and have no internal continuity breaks - essential for Class A quality surfacing. Bezier is a sub-set of the Non-Uniform Rational B-Spline (NURBS) math used by Alias. This means that all the expertise and experience you have using Bezier surfaces transfers easily to working with NURBS.
Alias uses NURBS in two ways: single-span and multi-span.