In system 40.1, with microcode 684, on LISP Machine Nine: In zmacs, if X is 0. evaluating the follwing with ctl-top-e (with no region) (DEFVAR Y (SETQ X (1+ X))) results in X and Y being 2. ie, the expresion is evaluated twice. If there is a region and ctl-top-e is used all works well.