# Point (typography)

(Redirected from Truchet point)
Point
Unit systemtypographic unit
Unit oflength
Conversions
1 point in ...... is equal to ...
typographic units   1/12 picas
imperial/US units   1/72 in
metric (SI) units   0.3528 mm

In typography, the point is the smallest unit of measure. It is used for measuring font size, leading, and other items on a printed page. The size of the point has varied throughout the history of printing. Since the 18th century, the point's size has varied from 0.18 to 0.4 millimeters. Following the advent of desktop publishing in the 1980s and 1990s, digital printing has largely supplanted the letterpress printing and has established the DTP point (desktop publishing point) as the de facto standard. The DTP point is defined as ​172 of an international inch (about 0.353 mm) and, as with earlier American point sizes, is considered to be ​112 of a pica.

In metal type, the point size of the font described the height of the metal body on which the typeface's characters were cast. In digital type, letters of a font are designed around an imaginary space called an em square. When a point size of a font is specified, the font is scaled so that its em square has a side length of that particular length in points. Although the letters of a font usually fit within the font's em square, there is not necessarily any size relationship between the two, so the point size does not necessarily correspond to any measurement of the size of the letters on the printed page.[1][2]

## History

The point was first established by the Milanese typographer, Francesco Torniella da Novara (c. 1490 – 1589) in his 1517 alphabet, L'Alfabeto. The construction of the alphabet is the first based on logical measurement called "Punto," which corresponds to the ninth part of the height of the letters or the thickness of the principal stroke.[3][4]

## Notations

A measurement in points can be represented in three different ways. For example, 14 points (1 pica plus 2 points) can be written:

• 1P2p (12 points would be just "​1P ")—traditional style
• 1p2 (12 points would be just "1p")—format for desktop
• 14pt (12 points would be "12pt" or "1pc" since it is the same as 1 pica)—format used by Cascading Style Sheets defined by the World Wide Web Consortium.[5]

## Varying standards

### Comparison table

Various point definitions
Name Year mm inch
≈ 0.350 mm
Fournier[6] 1737 ≈ 0.345  0.0135
American 1886 ≈ 0.3515 0.013837
Japanese[7] 1962 0.3514 ≈ 0.013835
TeX `pt` 1982 = 0.35145980 ≈ 0.013837 = ​172.27
PostScript, CSS `pt`, TeX `bp` 1984 = 0.3527 = 0.0138 = ​172
≈ 0.375 mm
Didot 1783 ≈ 0.375972 ≈ 0.0148
Berthold 1878 ≈ 0.376 ≈ 0.014801
German actual,[8] TeX `dd` 1964 0.376065 ≈ 0.014806
German nominal[8] 1984 0.375 ≈ 0.014764
Other
Truchet 1694 ≈ 0.188 ≈ 0.007401
L'Imprimerie Nationale 1810 = 0.400 ≈ 0.015748
German,[9] Japanese, CSS `q` 1999 0.250 ≈ 0.009842

There have been many definitions of a "point" since the advent of typography. Traditional continental European points at about 0.375 mm are usually a bit larger than English points at around 0.350 mm.

### French points

The Truchet point, the first modern typographic point, was 1/144 of a French inch or 1/1728 of the royal foot. It was invented by the French clergyman Sébastien Truchet. During the metrication of France amid its revolution, a 1799 law declared the meter to be exactly 443.296 French lines long. This established a length to the royal foot of 9000/27706 m or about 325 mm, which made the Truchet point equal to 15625/83118 mm or about 0.187986 mm. It has also been cited as exactly 0.188 mm.

The Fournier point was established by Pierre Simon Fournier in 1737.[10][11][12]:60–66 The system of Fournier was based on a foot, 1 foot equals 12 inches, 1 inch (pouce) was divided into 12 lines (lignes) and 1 line was further divided into 6 typographic points (points typographiques). 1 point Fournier = 0.0135 inches.

The Fournier scale: two inches in total, divided into four half-inches, the medium intervals are one line (​112 inch), and the smallest intervals are ​136 inch; no intervals for the point is given, though

Fournier printed a reference scale of 144 points over two inches; however, it was too rough to accurately measure a single point.[11]

The Didot point, established by François-Ambroise Didot in 1783,[13] was an attempt to improve the Fournier system. He did not change the subdivisions (1 inch = 12 lines = 72 points), but defined it strictly in terms of the royal foot, a legal length measure in France: the Didot point is exactly 1/864 of a French foot or 1/72 of a French inch, that is (by 1799) 15625/41559 mm or about 0.375972 mm. Accordingly, one Didot point is exactly two Truchet points.

However, 12 Fournier points turned out to be 11 Didot points,[11]:142–145 giving a Fournier point of about 0.345 mm; later sources[12]:60–61 state it as being 0.34875 mm. In Belgium the Fournier system was used until the 1970s and later. It was called the "mediaan"-system. To avoid confusion between the new and the old sizes, Didot also rejected the traditional names, thus parisienne became corps 5, nonpareille became corps 6, and so on.[11]:143 The Didot system prevailed because the French government demanded printing in Didot measurements.[14][better source needed]

The Fournier point did not achieve lasting popularity despite being revived by the Monotype Corporation in 1927.[citation needed] It was still a standard in Belgium, in parts of Austria, and in Northern France at the beginning of the 20th century.[12]:66

### Other European points

Approximations were subsequently employed, largely owing to the Didot point's unwieldy conversion to metric units (the divisor of its conversion ratio has the prime factorization of 3×7×1979).

In 1878 Hermann Berthold defined 798 points as being equal to 30 cm, or 2660 points equalling 1 meter: that gives around 0.376 mm to the point.[15][16][17][18] A more precise number,0.376065 mm, sometimes is given;[16] this is used by TeX as the `dd` unit. This has become the standard in Germany[8] and Central and Eastern Europe.[19] This size is still mentioned in the technical regulations of the Eurasian Economic Union.[20]

### Metric points

TeX also supports a new Didot point (nd) at 3/8 mm or 0.375 mm and cites a 1978 redefinition for it.[citation needed] The French National Print Office adopted a point of 2/5 mm or 0.400 mm in about 1810 and continues to use this measurement today (though "recalibrated" to 0.39877 mm).[21][22][23]

Japanese[24] and German[9][16][18] standardization bodies instead opted for a metric typographic base measure of exactly 1/4 mm or 0.250 mm, which is sometimes referred to as the quart in Japan. The symbol Q us used in Japanese after the initial letter of quarter millimeter. Due to demand by Japanese typesetters, CSS adopted Q in 2015.[25][26]

### American points

The basic unit of measurements in American typography was the pica,[27][12][28] usually approximated as one sixth of an inch, but the exact size was not standardized, and various type foundries had been using their own.[12]

After the American war of Independence Benjamin Franklin was sent as commissioner (Ambassador) for the United States to France (December 1776 to 1785).[29] Whilst there he had intimate contact with the Fournier family, including the father and Pierre Simon Fournier. Franklin wanted to teach his grandson printing and typefounding, and arranged him to be trained by Francois Ambroise Didot. Franklin bought also matrices and more equipment in order to set up a type-foundry for Bache and brought this with him, when he returned to Philadelphia. Around 1790 Bache published a specimen sheet with some Fournier types. [30] [31] After the death of Franklin, the matrices and the Fournier mould were acquired by Binny and Ronaldson, the first permanent type-foundry in America. In 1833 this plant was merged into the firm that in 1860 was renamed in Mackellar, Smith and Jordan. The Fournier cicero mould was used by them to cast pica-sized type.

Nelson Hawks proposed, like Fournier, to divide one American inch exactly into six picas, and one pica into 12 points. However, this saw an opposition because the majority of foundries had been using picas less than one sixth of an inch. So in 1886, after some examination of various picas, the Type Founders Association of the United States approved the pica of the MacKellar, Smiths, & Jordan Co. foundry of Philadelphia (previously L. Johnson & Co., hence the Johnson pica) as the most established.[27] The official definition of one pica is 0.166044 inches (4.2175 mm), and one point is 0.013837 inches (0.3515 mm). That means 6 picas or 72 points constitute 0.99624 standard inches. A less precise definition is one pica equals 0.166 inches (4.2 mm), and one point 0.01383 inches (0.351 mm).[27][32] It was also noticed that 83 picas is nearly equal to 35 cm, so the Type Founders Association also suggested using a 35 cm metal rod for measurements, but this was not accepted by every foundry.[27]

This has become known as the American point system.[32][27] The British foundries accepted this in 1898.

In modern times this size of the point has been approximated as exactly ​172.27 (0.01383700013837) of the inch[33] by Donald Knuth for the default unit of his TeX computer typesetting system and is thus sometimes known as the TeX point, which is 0.35145980 mm.

### Desktop publishing point

The desktop publishing point (DTP point) or PostScript point is defined as ​172 or 0.0138 of the international inch, making it equivalent to 0.3527 mm. Twelve points make up a pica, and six picas make an inch.

This specification was developed by John Warnock and Charles Geschke when they created Adobe PostScript. It was adopted by Apple Computer as the standard for the display resolution of the original Macintosh desktop computer and the print resolution for the LaserWriter printer.[34][35]

In 1996, it was adopted by W3C for Cascading Stylesheets (CSS) where it was later related at a fixed 4:3 ratio to the pixel due to a general (but wrong) assumption of 96 pixel-per-inch screens.

## Font sizes

In lead typecasting, most font sizes commonly used in printing have conventional names that differ by country, language and the type of points used.

Desktop publishing software and word processors intended for office and personal use often have a list of suggested font sizes in their user interface, but they are not named and usually an arbitrary value can be entered manually. Microsoft Word, for instance, suggests every even size between 8 and 28 points and, additionally, 9, 11, 36, 48 and 72 points, i.e. the larger sizes equal 3, 4 and 6 picas. While most software nowadays defaults to DTP points, many allow other units, especially code-based systems like TeX and CSS.

## References

1. ^ Phinney, Thomas (16 August 2012). "Point Size and the Em Square: Not What People Think". Phinney on Fonts. Retrieved 26 February 2018.
2. ^ "15.7. Font size: the 'font-size' property", Cascading Style Sheets Level 2 Revision 2 (CSS 2.2) Specification, World Wide Web Consortium, 12 April 2016, retrieved 26 February 2018
3. ^ Giovanni Mardersteig (1971). The alphabet of Francesco Torniello da Novara [1517]: Followed by a comparison with the alphabet of Fra Luca Pacioli. Officina Bodoni.
4. ^ Healey, Robin (2011). Italian Literature Before 1900 in English Translation: An Annotated Bibliography, 1929-2008. University of Toronto Press. ISBN 9781442642690.
5. ^ "4.3.2. Lengths", Cascading Style Sheets, level 2 CSS2 Specification, World Wide Web Consortium, 12 April 2016, retrieved 26 February 2018
6. ^ Various sources give different sizes, namely: ≈ 0.0135 in, ≈ 0.0137 in, ≈ 0.345 mm, (exactly) 0.34875 mm, ≈ 0.349 mm, ≈ 0.35 mm.
7. ^ JIS Z 8305. 活字の基準寸法. Dimensions of Printing Types.
8. ^ a b c DIN 16507-1:1998 and its predecessors, at least since 1964, for lead typecasting defined 2660 points to measure 1000.333 mm at 20 °C, but for public communication it later introduced a rounder value.
9. ^ a b DIN 16507-2 (1984, 1999) does not specify a custom unit for electronic typography, but measures using a module.
10. ^ Fournier, Pierre Simon (1764). Manuel typographique. pp. 125–138.
11. ^ a b c d De Vinne, Theodore Low (1900). The practice of typography. 1. New York: Century Co. pp. 133–145.
12. Legros, Lucien Alphonse; Grant, John Cameron (1916). Typographical Printing-Surfaces. London and New York: Longmann, Green, and Co. pp. 57–60.
13. ^ Baines, Phil; Haslam, Andrew (2005). Type & Typography. Laurence King Publishing. p. 93. ISBN 978-1-85669-437-7.
14. ^ L. Ronner, Van leerling tot Zetter, 1913, N.V.De nieuwe Tijd, Amsterdam, pag 30.
15. ^ Smalian, Hermann (1899). "Type Systems of To-day". The British Printer. XII (68): 130–131. They commissioned for this purpose the well-known Berlin brass rule manufacturer, H. Berthold, who supplies brass rules not only to most of the German foundries but also to many foreign houses, and he, in conjunction with Prof. W. Fürster, the chief director of the Berlin Observatory, agreed that 2660 typographical points of the Didot system should correspond to one metre. Accordingly the Standard Gauge Commission in Berlin in 1879 arranged a standard measure of 30 centimetres = 133 nonpareil or 798 typographical points, and gave a copy to all the German foundries, and since that time disputes about the Didot depth were unknown in Germany.
16. ^ a b c Brekle, Herbert E. (1994). "Typographie". Schrift und Schriftlichkeit / Writing and its Use. Walter de Gruyter. p. 210ff. ISBN 978-3-11-020323-3.
17. ^ Funke, Fritz (1998). Buchkunde. De Gruyter. p. 194. ISBN 978-3-11-094929-2.
18. ^ a b Blana, Hubert (1999). Die Herstellung: Ein Handbuch für die Gestaltung, Technik und Kalkulation von Buch, Zeitschrift und Zeitung. Walter de Gruyter. p. 101. ISBN 978-3-11-096787-6.
19. ^ (in Russian) "§1.3". GOST 3489.1-71. Printing types (Russian and Roman graphic bases). Group arrangement. Indexing. Base line. Characters per 4 picas ГОСТ 3489.1-71. Шрифты типографские (на русской и латинской графических основах). Группировка. Индексация. Линия шрифта. Емкость. Кегль измеряется в типографских пунктах. Типографский пункт равен 0,376 мм.
20. ^ (in Russian) Статья 8. Пункт 11. // ТР ТС 007/2011. Требования безопасности издательской (книжной и журнальной) продукции, школьно-письменных принадлежностей.
21. ^ Mosley, James (1997). "French academicians and modern typography: designing new types in the 1690s". Typography papers (2): 5–29. The point in current use at the Imprimerie Nationale measures 0.39877 mm. This appears to be the result of a 'recalibration', for which no date can be given, of the point of 0.4 mm.
22. ^ Bulletin du bibliophile. 2002. p. 73. These latter figures give the size in the 'points millimétriques' of about 0.4 mm that are said to have been introduced at the Imprimerie impériale by Firmin Didot and which are the basis for the 'point IN' used today at the Imprimerie nationale.
23. ^ "Type bodies compared". Typefoundry. 30 April 2008.
24. ^ JIS X 4052:2000, JIS Z 8125:2004
25. ^ "CSS Values and Units Module Level 3". World Wide Web Consortium. 29 September 2016.
26. ^ "CSS Values and Units Module Level 3". World Wide Web Consortium. 11 June 2015.
27. De Vinne, Theodore Low (1900). The practice of typography. 1. New York: Century Co. pp. 145–156.
28. ^ Hyde, Grant Milnor (1920). Newspaper Editing: A Manual for Editors, Copyreaders, and Students of Newspaper Desk Work. New York and London: D. Appleton and Company. pp. 226–227.
29. ^ Benjamin Franklin papers, Kislak Center for Special Collections, Rare Books and Manuscripts, University of Pennsylvania
30. ^ Updike, I, p. 257, II pp. 152-3
31. ^ Allen Huet, Fournier the compleat typographer, 1972, London, Frederik Muller Ltd, page 3, 4, 62, 63
32. ^ a b "The American Point System". American printer and lithographer. 11: 89. 1890.
33. ^ Knuth, Donald E. (1990). The TeXbook (17th revised ed.). Addison-Wesley. p. 58.
34. ^ Tucker, H. A. (1988). "Desktop Publishing". In Ruiter, Maurice M. de. Advances in Computer Graphics III. Springer. p. 296. ISBN 3-540-18788-X.
35. ^ Spring, Michael B. (1991). Electronic printing and publishing: the document processing revolution. CRC Press. p. 46. ISBN 0-8247-8544-4.