The item discussed in https://groups.google.com/forum/#!searchin/comp.lang.lisp/pierpaolo$20bernar... needs a clarification, and I don't see it listed in the wiki page. Can somebody add it, or should I do it myself? I lost track of what wiki page is the currently cared for one.
TL;DR:
(format nil "~@D" 0) ==> ? (currently unclear)
KMP wrote in that thread: "I would argue for clarifying this as "+0" in a future standard.". Everybody else seemed to substantially agree.