The style of binding applied to books used for written records, e.g., blankbooks, is by necessity much different from that for books meant to be read. Their shape, size, and durability depend on the purpose for which they are intended; consequently, stationery bindings vary greatly in style, complexity, and quantity. Blankbooks, including court record books, which are generally required for permanent records, are bound in a different style from letterpress work because not only must the binding withstand heavy use, it must also open very flat for writing purposes. See: SPRING BACK . To a large extent, loose-leaf books are replacing sewn blankbooks, but this branch of stationery binding is rather specialized and is not often undertaken by printing establishments. Manifold and other books designed for use with carbon paper, of which there is a tremendous variety, are generally of a less permanent nature and in most cases are bound in various styles of CUT FLUSH bindings appropriate to the intended use. Stationery binding is sometimes referred to as "vellum binding" because at one time the books were generally covered in vellum. See also: BLANKBOOK BINDING ;MECHANICAL BINDING ;RULING .