Machine tools; hand-held tools, other than hand-operated; portable electric power tools including saws, circular saws, jig-saws, drills, planers, sanders and grinders; parts, fittings, accessories or attachments for any one of the aforesaid including guides adapted to guide a portable electric power tool in a straight line; saw guides adapted to guide a portable electric saw to make a linear cut at a selectable variable angle; holding devices for machine tools