Some slide rules ("duplex" models) have scales on both sides of the rule and slide strip, others on one side of the outer strips and both sides of the slide strip, still others on one side only ("simplex" rules). A sliding cursor with a vertical alignment line is used to find corresponding points on scales that are not next to each other or, in duplex models, are on the other side of the rule. The cursor can also record an intermediate result on any of the scales.