> My question is: Am I guaranteed that reverse(args( ... )) is the correct order?
For addition and assuming that the option variable display_format_internal is false, the answer is yes.
The function inpart might be useful to you--to read the user documentation, enter ?? inpart. Also, to print
the internal representation of an expression, try the CL function print--either
(%i7) e : a + b + 42 * z;
(%o7) 42*z+b+a
(%i8) :lisp(print $e)
((MPLUS SIMP) $A $B ((MTIMES SIMP) 42 $Z))
((MPLUS SIMP) $A $B ((MTIMES SIMP) 42 $Z))
(%i8) ?print(e);
((MPLUS SIMP) $A $B ((MTIMES SIMP) 42 $Z))
(%o8) 42*z+b+a
--bw