Variation folding allows side variations to be expanded and collapsed. Folding can make it easier to concentrate on the main line or important side lines when a game is annotated with many side variations. Folding is turned on in the annotation window, or can be turned on by using the 'f' or 'F' key (fold/unfold current variation or fold all/unfold all variation keys). Once on, you can click on the variation toggle button in front of each variation to open and close any particular variation (or use the 'f' key to toggle the variation fold when inside a variation).