+ or = zoom in - zoom out * zoom to extents Home go to the top sheet Delete or Backspace go to the next higher sheet in hierarchy PgUp go to the previous sheet in sequence PgDn go to the next sheet in sequence Up or Down invoke the revision history (WIP) Tab toggle between old and new revision Esc cancel current action (exit history, close pop-up, de-highlight glabel, close help) H show/hide help window D when comparing revisions, show difference N show newer sheet O show older sheet Q quit the viewer