I'm actually against this idea. There are lots of miscellaneous term scattered around the book already with no clear place to find them, the definition of "Basic Saving Throw" would be something easy to overlook. People are already upset about how much cross-checking and indexing they have to do to learn the system, I don't think we need to make that problem worse. Maybe if you release a Rules Compendium designed for people very experienced with the system, but for the beginner's rulebook you should focus on cutting down the multitude of game terms that need to be learned.
