Indeed, Fran. Most 3D modelers allow you to actually change the shapes involved. Meaning that if you have a 6-faced cube and tore a hole through it with a 16-faced cyclinder, your resulting object would actually contain this geometry. Bryce does boolean modeling by way of filtering, telling the raytracer that an object is either visible, not, or visible and casting textures. So booleans don't work the same (or as well, I might add!) in most other programs because what's happening is weird tesselation effects and inaccuracies. The advantage in other programs though is that you can seriously reduce unnecessary geometry at rendertime, and this is also part of the reason why Bryce's rendering engine is so slow.