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In Typography , a point is the smallest Unit of measure, it being the subdivision of the Pica . It is commonly abbreviated as '''pt.''' The traditional printer's point from the era of hot metal typesetting and presswork varied between 0.18 and 0.4 mm depending on various definitions of the Foot . Today, the traditional point has been supplanted by the desktop publishing point (also called the PostScript point), which has been rounded to an even 72 points to the Inch (1 point = 0.3527 mm). In either system, there are 12 points to the pica. THE FRENCH PRINTER'S POINTS ''Foreword concerning the conversion from the Old French Royal Units to the decimal SI unit of length:'' The French law of 1799 that defined the Metre stated the meter to be exactly 443.296 French lines, or 3 French Feet , 0 French inches and 11.296 French lines. The Pied du Roi, or French Royal foot, is exactly 9000/27706 metres, or about 0.324839385 m. This conversion value is used below. Truchet's point The modern typographic point was invented in France by the clergyman Sébastien Truchet (1657-1729). The size he chose was such that 1728 of these made one Pied du Roi; i.e., 15 625 / 83 118 ≤ 0.187 985 755 2 mm. Fournier's point Pierre Simon Fournier (1712-1768) used a typographic point of about 11 / 864 French Royal inches ≈ 0.345 mm. Fournier's point did not achieve lasting popularity. Didot's point
This odd value – due to the divisor 41 559 (prime factors: 3 x 7 x 1979) – was not very flexible for use by typesetters and printers. So, though the general size of the Didot point continued to be preferred to that of Truchet, several other printers each chose his or her own value for the point. These are compared below by their own equivalent length of the old Pied du Roi – i.e., the length that 864 of their points add up to:
''Or even, according to a proposal of the year 1975, but never applied:''
Note, that the adopted a point of 0.4 mm exactly and continues to use it today. The Didot point has been replaced by the DTP point in France and throughout the world. THE TRADITIONAL AMERICAN POINT SYSTEM ''By the (Kasson) Metric Act (1866), Public Law 39-183, the ''U.S. Survey foot'' is 1200/3937 m. However, this is only 0.0002 % more than the anglo-saxon compromise foot (1959) used below.''
In 1886, the Fifteenth Meeting of the Type Founders Association of the United States approved the so-called "Johnson pica" be adopted as the official standard. This makes ''the traditional American printer's foot'' measure 11.952 inches or 303.5808 mm exactly (approximately 1/72.27 of an inch), at last by respecting the conversion values of 1959 and not the values of 1886. Just like the French Didot point, the traditional American printer's point was replaced in the 1980s by the current computer DTP point system. CURRENT DTP POINT SYSTEM The desk-top publishing point (DTP point) is defined as 1/72 of the anglo-saxon compromise Inch of 1959 (25.4 mm), it is approximately '''0.0139 inch''' or '''0.3528 mm'''. Twelve points make up a pica, and six picas make an inch. The point is the standard unit for measuring Font size and Leading and other minute items on a printed page. This system was notably promoted by John Warnock and Charles Geschke , the inventors of Adobe PostScript , and it is therefore it is sometimes also called ''PostScript point''. In metal type, the point size of the Font described the size (height) of the metal body on which the Typeface 's characters were cast. In digital type, the body is now an imaginary design space, but is used as the basis from which the type is scaled (see Em ). A measurement in Pica s is usually represented by placing a lower case p after the number, such as "10p" means "10 picas". Points are represented by placing the number of points after the p, such as 0p5 for "5 points," 6p2 for "6 picas and 2 points", or 1p1 for "13 points" which is converted to a mixed fraction of 1 pica and 1 point. (An alternate nomenclature is described in the Pica article.) The TeX typesetting system predates PostScript slightly and uses a point of 1/72.27 inch or 0.3515 mm, commonly called the ''TeX point.'' SEE ALSO EXTERNAL LINKS |
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