Fortunately for revolutionaries, bibliographers were not consulted by governments on such matters until the very late nineteenth century. The Lettering of Signatures Catchwords ensure that a group of pages may be printed in the proper order on each large sheet of paper. Like catchwords, signatures were taken over by the early printers from medieval manuscript practice. Among these last was a Methodist printer in Bristol, a friend of John Wesley, who may have been attracted to the initial letter. The practice was revived in the nineteenth century, especially in America, and is now current, at least when signatures are used at all.
Numbers have the advantage of extending on into infinity.
Letters as signatures must be repeated with distinguishing variations if the book is of some length. Many further variations of signatures are known to be possible, and others await discovery. Their detection offers the scholar, or even the casual reader, one of the few excuses for extended idle browsing in old books. Particularly noticeable are variations in the signatures of preliminary pages. Authors tend to write their prefaces last of all, often when the book is already on press.