Scott,
I don't really have any strong objections to your description insofar as it applies to char* in the context of "C Strings", but I completely disagree with extending it to uuid.
Yes, I think I've explained that my usage of it is mostly historical and habitual. Also, we've established that "invalid" is not the ideal description. Still, I cannot see anyone coming out with a better name to classify nil, null and the like. Until then, I guess, I'll probably keep using "invalid" (not in spite but merely as the closest *I* can come up with). Consider my usage of it in broader sense (as you did with pointers). By now we all understand in what context it is used and we can put this one to rest -- we still have plenty to debate about, right? Peace, V.