Warning: keybing for 'ace-jump-mode-pop-mark `Cx-SPC` already in use..

[touxstone]

Hi, just trying to clarify: is it not "C-x SPC" already in use? It runs the command rectangle-mark-mode (found in global-map) which is an interactive autoloaded compiled Lisp function in rect.el & already part of Emacs. Though on line 10 of the ace-jump-mode preamble it reads that this file, the ace-jump-mode is (also?) part of Emacs?. It may cause confusion is not it?