By now you're probably wondering why I've embarked on the XML crusade and what it has to do with Lisp (after all, Lisp was created about thirty years before XML). I promise that everything will become clear soon enough. But before we take our second step, let's go through a small philosophical exercise. Take a good look at the XML version of our "add" function above. How would you classify it? Is it data or code? If you think about it for a moment you'll realize that there are good reasons to put this XML snippet into both categories. It's XML and it's just information encoded in a standardized format. We've already determined that it can be generated from a tree data structure in memory (that's effectively what GCC-XML does). It's lying around in a file with no apparent way to execute it. We can parse it into a tree of XML nodes and do various transformations on it. It's data. But wait a moment! When all is said and done it's the same "add" function written with a different syntax,... - Glenn Slaven