4335. Technical terms relative to Books, Engravings, etc:
4336. Books are distinguished according to the number of pages in a sheet of the paper on which they are printed; as, two leaves, four pages, folio; four leaves, eight pages, quarto, or 4to.; eight leaves, sixteen pages, octavo, or 8vo.; twelve leaves, twenty-four pages, twelves, duodecimo, or 12mo.; sixteen leaves, thirty-two pages, sixteens, or 16mo.; eighteen leaves, thirty-six pages, octodecimo, eighteens, or 18mo.
4337. The size of a book is determined by the size or designation of a sheet of the paper on which it is printed; as foolscap 4to., or 8vo.; post 8vo.; demy 8vo; royal 8vo. &c.
4338. The letters A, B, C, D, &c., and the letters and figures, A 2, A 3, A 4, &c., at the bottoms of the first, third, fifth, seventh, &c., pages of printed sheets, are marks for directing the printer, bookseller, and bookbinder in collecting, collating, folding and placing the sheets in proper order. These marks are usually termed signatures.
4339. When the page of a book is divided into two or more parts by a line or lines, or blank spaces, running from the top to the bottom, each division is called a column. This work is printed in columns.