well, i just gotta say, that i do question the backward-compatibility of the symbols, you've chosen... BUT i definitely like the concept of using some "most" and "least" operator. :-)

i didn't really follow you completely -> if you meant the "equal to the least" could equal undefined or not. If you did - my only thought is that it should equal the last defined value instead, because it would seem while reading any file, array, etc - the last operation of it would always be to return undefined (if i understand that whole process correctly). That would make that operator just a duplicate of testing for undef.

but anyways - i like your ideas :-)