[asdf-devel] textual representation of plan, asdf:explain

What is the way to get a textual representation of the plan of a system? I would have thought that this is what ASDF:EXPLAIN is for, but grepping through asdf.lisp did not make me believe that's true. Also, is there some fundamental reason why (asdf:explain 'asdf:compile-op :system-name) could not be the interface for ASDF:EXPLAIN? -T.