A book is dated by its back cover, not its front

① The one-line version

No book number before 1967, no bar code before the mid-1980s, SBN not ISBN on a British book until 1974, shillings and pence until 15 February 1971, net on a British hardback until 1997, thirteen digits from 2007, the euro from 2002 — and a spine that reads the way its country read.

② The book number and the bars

What	From	Notes
SBN, nine digits	1967 (UK)	The Standard Book Number. British books printed the name “SBN” until 1974.
ISBN, ten digits	1970	ISO 2108. America from about 1968–70; France and Germany from about 1972; Italy and Spain 1973; Greece late 1970s. Before the date for the country, the cover carries no number at all.
Bookland EAN bar code	c. 1985 US, c. 1987–88 Europe	The 978 prefix was agreed about 1980; the American guidelines date from 1985. A bar code on a 1979 paperback is the easiest anachronism there is.
Price add-on	with the bars	Five digits beside the bars: a leading 5 is US dollars, 90000 means no price.
ISBN-13	1 Jan 2007	Books of 2005–06 commonly print both forms.

Every number the studio prints is invented, and because an invented number with a correct check digit could belong to a real book, the check digit is deliberately wrong by default. The bars look right to a camera and no till will accept them. The Print panel can turn that off.

③ The price, in the money of the year

• Britain: “7s. 6d. net” on a hardback, “3/6” on a paperback, until decimalisation on 15 February 1971; both prices for a few years around it; “net” on hardbacks until the Net Book Agreement ended in 1995–97; then .95 and .99.
• America: the hardback price on the front flap; the rack paperback’s in the front corner and at the head of the spine — 25¢ in 1939, 35¢ in the fifties, about $1.50 by the mid-seventies.
• France: francs, new francs (NF) 1960–62, francs again, the euro from 2002. Germany: Mark and Pfennig, Reichsmark, Deutsche Mark from 20 June 1948, the euro. Italy: L. with a dot for the thousands, both currencies at the turn of the century. Spain: P.V.P. in pesetas. Greece: ΤΙΜΗ ΔΡΑΧΜΑΙ in katharevousa before about 1976, then ΔΡΧ., then the euro.

④ The spine: how wide, and which way

Width is arithmetic: the page count times the thickness of a leaf of the paper, plus two boards on a hardback. Novel paper runs about 400–450 pages to the inch; pulp is bulkier, war-economy paper thinner, bible paper up to three times thinner. Below about 5 mm a printer leaves the spine blank.

• Top to bottom (the title reads when the book lies face up): America, modern Britain, Scandinavia, the Netherlands — and the recommendation of ISO 6357 and BS 6738.
• Bottom to top: Germany, France, Spain, and British books before about 1960, whose early paperback series ran upward. Italy used both.
• Across: thick nineteenth-century books and cloth cases, lettered in short stacked lines between gilt bands.
• Greece could not be confirmed. The studio defaults to upward before 1990 and downward after; the Look panel changes it.

⑤ What a jacket carries, and where

Laid flat, a jacket is flap · back · spine · front · flap. Each panel is the board plus about 3 mm; the flaps widen through the century, from 60–80 mm before the war to 80–100 mm today. The front flap carries the blurb and, from the 1910s, the price in its top corner — which is why second-hand jackets are “price-clipped”. The back flap carries the author and, from mid-century, the author’s photograph and the jacket designer’s credit. The back panel carries praise, the house’s other books, and from the 1980s the bar code.

⑥ Sizes

Where	Trims (height × width)
Britain, before 1970	Crown octavo 191 × 127, Demy octavo 222 × 143, Royal octavo 254 × 159 mm; the paperback series size 181 × 111 mm
Britain, metric	Crown 186 × 123, Demy 216 × 138, Royal 234 × 156; paperbacks A 178 × 110, B 198 × 129, C 216 × 135 mm
America	5½ × 8½, 6 × 9, 6.14 × 9.21 in; the rack paperback 4¼ × 6⅞ in
France, Germany	roughly 14 × 20.5 cm literary, 11 × 18 cm poche; Taschenbuch 12.5 × 19 cm
Italy, Spain, Greece	13 × 20, 14 × 21, 15 × 21 and 17 × 24 cm
Comics	America 197 × 267 mm in the Golden Age, 168 × 259 today; the British weekly about 215 × 290; the Franco-Belgian album about 22 × 29.5 cm

⑦ Series conventions — imitated, never copied

Several of the looks a period audience recognises belonged to one house. The studio draws the convention — the layout, the colour logic, the kind of type — with its own names, its own devices and nobody’s trade dress:

• Three horizontal bands, coloured by genre — a thirties convention several series shared (Albatross 1932, the British sixpenny series from 1935).
• A grid of bands at the head with a picture below — the early sixties.
• Cream with a double rule, the author in black and the title in red — the continental literary cover, essentially unchanged since before the First World War.
• The whole cover in the series colour with a framed picture — the continental crime series.
• The painted rack paperback — America from 1939, Britain in the fifties and sixties.
• The numbered weekly booklet — the German Heftroman, the Spanish novela popular, the Greek φυλλάδιο.

⑧ The decade look

Decorated cloth to the 1910s, Art Nouveau from the 1890s; Art Deco jackets between the wars; two-colour economy in the 1940s (paper rationing from 1940, the Book Production War Economy Standard of 1942); painted realism and modernist grids in the fifties and sixties; photography and airbrush in the seventies; foil and embossed author names in the eighties; the soft-focus photograph from the nineties; hand-lettering and big type in the 2010s; the flat “blob” cover after that.

⑨ Type, and two languages that changed

• German: Fraktur on a German cover until the decree of 3 January 1941 that made Antiqua the normal type; science and some modern houses used Antiqua before it. Fraktur is never set in capitals.
• Greek: polytonic until the reform of 1982, and katharevousa in the imprint (ΑΘΗΝΑΙ) before about 1976. Greek capitals carry no accents, which is why the studio sets an old Greek cover in capitals: correct either side of the reform.

⑩ The other things with covers

• Exercise books: name, subject and class on the front; on the back the tables the country taught — twelve pence to the shilling in Britain before 1971, the tavola pitagorica in Italy, the προπαίδεια in Greece. The American composition book is black-and-white marble.
• Diaries and ledgers: the year blocked on the cover; the ledger in quarter leather with corners and spine labels; the police pocket book numbered; the reporter’s notebook bound at the top.
• Comics: the corner box, the cover date two or three months ahead of sale, the price that moved every few years, and from 1955 to 2011 an approval seal — which, being a mark, the studio replaces with an invented one.
• Wear: the sunned spine, fox spots, rubbed corners, reading creases on a paperback spine, a price-clipped flap, the library’s label and stamp.

⑪ Portugal, the Netherlands, Turkey and Russia

Four markets added in September 2026. Two limits hold in every studio: Turkey starts in 1928, the year the Latin alphabet replaced the Arabic script (an earlier Turkish sheet would be Ottoman, which no studio sets), and Russian before 1918 is spelled by rule — the hard sign on every word ending in a consonant and і before a vowel are placed automatically; the yat (ѣ) cannot be derived from modern spelling and is left as е. Turkish capitals keep their dots: i goes to İ and ı to I, so İSTANBUL, never ISTANBUL.

Country	What the studio changes, and when
Portugal	ISBN group 972; prices in escudos with the cifrão and then euros; the imprint city (Porto, Lisboa).
Netherlands	ISBN group 90; guilders then euros.
Turkey	ISBN group 975; from 1928; İstanbul with its dot.
Russia	ISBN group 5, and only from 1987; the Soviet sheet sizes given as fractions (84×108/32); the imprint city by date — С.-ПЕТЕРБУРГЪ before 1918, Петроград to 1924, then Ленинград; the old orthography before 1918.

⑫ What we could not verify

• Which way Greek spines read, decade by decade. It is a default in the studio, and editable.
• Pre-war flap widths and the dates finishes such as matt lamination, soft-touch and spot UV arrived.
• The wording on the front and back of a Greek exercise book before the 1970s.
• Prices are anchored to a new book of the kind in that year and interpolated between anchors: right in size and in form, not a quotation from a catalogue.
• Titles, authors, publishers, series and reviewers are invented in each language and were not checked against a catalogue of every book ever printed. The Checks panel flags the real houses it knows by name.