\key{{\bf abort} partially typed or executing command}{C-g}
\metax{{\bf recover} a file lost by a system crash}{M-x recover-file}
-\key{{\bf undo} an unwanted change}{C-x u {\rm or} C-_}
+\metax{{\bf undo} an unwanted change}{C-x u, C-_ {\rm or} C-/}
\metax{restore a buffer to its original contents}{M-x revert-buffer}
\key{redraw garbaged screen}{C-l}