Executable XML users challenge

provide any LISP macro with clear explanation of its structure and function
that is :
1.concise (max 10 lines)
2.does not have a C equivalent(at least not anything above 100 lines)
3.does not use any libraries or imported complex functions which are not in C
If you provide an exact explanation/commentary on what it does i'll try to make a C solution which
is equivalent to LISP one. If i fail to do so, LISP wins, if i provide a solution you can make another macro.
If all examples in the thread are provide with C equivalents, LISP loses.

>>125
There's no way for that code to compare 0.0 to "Hello world" since the only function applied to "Hello world" is append (I have already said that, haven't I?) The given task explicitly states that only numbers (namely integers and floating point numbers) should be sorted, everything else are your assumptions only, and don't belong to the task scope.