The PathNode actor possibly is the most common NavigationPoint. It provides no additional script but has a texture which makes it possible to put it in a map using the Editor. The PathNodes usually build the backbone of the bot AI navigation system of a map. Pathnodes work the same in UT2003 as they did in UT, with the exception of a couple new properties that are inherited from UT2003's NavigationPoint class.
See Bot Navigation.