>But even then we spoke in terms of world coordinates vs. joint coordinates. World vs. joint coordinates might also generate some confusion, since joint coordi

>But even then we spoke in terms of world coordinates vs. joint coordinates. World vs. joint coordinates might also generate some confusion, since joint coordinates are "world" coordinates too. And you can refer to the coordinates of a joint using "world" coordinates, which someone could easily refer to as a "joint coordinate". Of course, you can formally define exactly what these terms mean, but then you've lost all of the advantage of using common terms rather than more formal terms since you've replaced the common meaning of those terms with a formal one.