Hi Bill,

Just to add to Michael's post, you also have to remember when using NURBS modellers and you want to 'connect' pieces together you usually 'Boolean Union' Solids bodies and 'Join' Surfaces, you can also use the Boolean functions on surfaces, like if you have overlapping planar surfaces on the same plane you can 'Boolean Union' them together to get one surface, but you can't 'Join' Solid bodies.

Hope this clarifies further