main printed feature: signature mark
Signature marks were used by printers to denote gatherings and leaves of a text so that they knew that the work was being printed and bound in the correct order. We typically use signature marks as a way of locating where something is in a book (e.g. “sig. B4v” indicates the verso side of the 4th leaf of the B gathering). But the style of a signature mark can also indicate where the book was printed.