When set to true, the start indent becomes the inside indent (closest to the binding), and the end indent becomes the outside indent (farthest from the binding).

This mirroring is typically used when generating signatures—groupings of pages printed together, folded, and bound into a booklet. In left-to-right documents, the first, third, etc. pages are printed on the left side of each sheet, and the second, fourth, etc. on the right. The reverse applies to right-to-left documents.