The front matter is often put into type after the composition of
the body has been completed, so that the number of pages is rarely
definitely determined at the beginning of the work. For this reason,
publishers have favored the expedient of numbering the preliminary
pages with roman folios, using the arabic folios for the text itself.
The front matter and the chapter pages running through the book
offer opportunities for embellishment and distinctive typographical
treatment, and therefore should be kept in exact accord, whether
elaborate decorations are used or the severest form of typographical
simplicity.