friction models

Hi, just wondering if anyone can explain/point me to some webpages, to explain some of the friction measurements used in some physics engines. Some engines, like dynamechs and newton use two values: static and kinetic friction. I remember these from school, f=kN, where static is the coefficient before the object is moving, and kinetic once the object has started moving. However ODE, uses a "coulomb friction coefficient" and I''m not really sure what this means, and how it relates to static&kinetic friction - is there a way to convert between the two systems? also, tokamak uses "friction" does anyone know what exactly that is meant to mean? Newton also has a ''softness'' force, is this just a fudge factor? Likewise for restitution, tokamak and Newton have this coefficient, but ODE just has a ''bounce'' force - what exactly is that? And dynamechs has a spring and dampner based system for ''bounces'' -- would there be any way to relate these coefficients to the coefficient for restitution? Thanks.