Bibliographic format

Bibliographic format (also known simply as "format") refers to the proportional relationship between a full sheet of paper and the folded and cut leaves of a book. For example, a text printed two-up so that the sheet of paper needs to be folded once to make the leaves of a book is in "folio" format. A book printed four-up on a sheet that's folded in half, then in half again, is a "quarto" and so on. Bibliographic format is usually determinable on books from the hand-press era (roughly 1450 to 1830), when books were routinely printed on hand-made sheets of paper. For machine-press books, it is usually impossible to tell the actual format of the book, regardless of any printed signatures present, unless it is bound loosely enough to see the sewing in the middle of the gatherings.

Same words, different meanings

Many of the same terms were long used as standard names for paper of various sizes (often known as "Imperial standard" size), the same way we now talk about "A4 paper" or "letter size paper". Then, beginning in the 19th century, the terms started being used to indicate a book's height: "octavo" means "little", "quarto" means "ordinary size", "folio" means "big", and "elephant folio" means "huge". Many libraries, including the Folger before 2023, use these size designations to describe sections of shelving in the stacks. For example, the Folger's "folios" section was for books with a spine height of 30.1 cm through 50 cm, or oblong with a width of 23.1 cm and up (anything bigger than that would have been in the "flats" section).

When someone associated with the Folger refered to "a folio," you had to rely on context to know if they mean an oversize book, a book in folio format, or one of the first four editions of Shakespeare's collected plays. Similarly, you have to know from context whether a researcher interested in the "the same work in different formats" is interested in different bibliographic formats, different media types (play, opera, movie, etc.), different carrier types (DVD, VHS tape, etc.), or what.

Bibliographic format in Folger catalog records

Catalog records for Folger vault material display the bibliographic format in parentheses at the end of the "Description" field, after the book's height (rounded up to the nearest centimeter) when applicable. Folger catalogers use the "DCRM(B)" abbreviations found in the left-hand column of the chart in this article. To search the catalog for books in a specific format, use the example in this link.

Abbreviations and names for formats

This chart lists abbreviations and names for each of the main bibliographic formats. The column on the far left shows the abbreviations used in the Folger catalog.

DCRM(B)	Gaskell	Ordinary spoken English	Latinate spoken English	Other
full-sheet	1⁰	broadsheet, full sheet
fol.	2⁰	folio	folio	fo., 1/2⁰, f⁰, F
4to	4⁰	quarto	quarto	1/4⁰, Q⁰, Q
8vo	8⁰	octavo	octavo	1/8⁰, O
12mo	12⁰	twelvemo	duodecimo	1/12⁰, D
long 12mo	long 12⁰	long twelvmo	long duodecimo
16mo	16⁰	sixteenmo	sextodecimo	1/16⁰, S
18mo	18⁰	eighteenmo	octodecimo	1/18⁰
24mo	24⁰	twenty-fourmo	vicesimo-quarto	1/24⁰, T
long 24mo	long 24⁰	long twenty-fourmo	long vicesimo-quarto
32mo	32⁰	thirty-twomo	trigesimo-secundo	1/32⁰, Tt
48mo	48⁰	forty-eightmo	quadragesimo-octavo	Fe
64mo	64⁰	sixty-fourmo	sexagesimo-quarto	1/64⁰, Sf
72mo	72⁰	seventy-twomo
96mo	96⁰	ninety-sixmo
128mo	128⁰	one-twenty-eightmo

NB. for search-and-replace updating to DCRM(B) abbreviations:

• character following the number may be:
  • degree symbol
  • superscript zero
  • superscript lower-case letter "o"
• be careful of the order of operations, e.g. change "12⁰" to "12mo" before changing" 2⁰" to"fol." or you'll end up with "1fol."

References