Editing Point (typography) (section)

=== Metric points ===
pdfTEX, but not plain TeX or LaTeX, also supports a ''new Didot point'' (''nd'') at {{frac|3|8}}&nbsp;mm or {{val|0.375|u=mm}} and refers to a not further specified 1978 redefinition for it.

{{anchor|Other French points}}
The [[French National Print Office]] adopted a point of {{frac|2|5}}&nbsp;mm or {{val|0.400|u=mm}} in about 1810 and continues to use this measurement today (though "recalibrated" to {{val|0.39877|u=mm}}).<ref name="Mosley1997">{{cite journal|last=Mosley|first=James|title=French academicians and modern typography: designing new types in the 1690s|journal=Typography Papers|issue=2|year=1997|pages=5–29|quote=The point in current use at the Imprimerie Nationale measures 0.39877&nbsp;mm. This appears to be the result of a 'recalibration', for which no date can be given, of the point of 0.4 mm.}}</ref><ref name="Bulletin du bibliophile">{{cite book|url=https://books.google.com/books?id=f-QVAQAAIAAJ&q=0.4+mm|title=Bulletin du bibliophile|date=2002|page=73|publisher=Promodis |isbn=9782765407768|quote=These latter figures give the size in the 'points millimétriques' of about 0.4&nbsp;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.}}</ref><ref>{{cite web|url=http://typefoundry.blogspot.ru/2008/04/type-bodies-compared.html|title=Type bodies compared|website=Typefoundry|date=30 April 2008}}</ref>
 
Japanese<ref name="JIS">JIS X 4052:2000, JIS Z 8125:2004</ref> and German<ref name="DIN 16507-2" /><ref name="Brekle1994" /><ref name="Blana1999" /> standardization bodies instead opted for a metric typographic base measure of exactly {{frac|1|4}}&nbsp;mm or {{val|0.250|u=mm}}, which is sometimes referred to as the ''quart'' in Japan. The symbol ''Q'' is used in Japanese after the initial letter of ''quarter millimeter''. Due to demand by Japanese typesetters, CSS adopted ''Q'' in 2015.<ref name="CSS-Q">{{cite web|url=https://www.w3.org/TR/css-values-3/#absolute-lengths|title=CSS Values and Units Module Level 3|work=World Wide Web Consortium|date=29 September 2016}}</ref><ref>{{cite web|url=https://www.w3.org/TR/2015/CR-css-values-3-20150611/#changes |title=CSS Values and Units Module Level 3|work=World Wide Web Consortium|date=11 June 2015}}</ref>

[[ISO 128]] specifies [[preferred number|preferred]] line thicknesses for [[technical drawing]]s and [[ISO 9175]] specifies respective pens. The steps between nominal sizes are based on a factor of √2 ≈ 1.414 in order to match [[ISO 216]] [[paper size]]s. Since the set of sizes includes thicknesses of 0.1&nbsp;mm, 0.5&nbsp;mm, 1&nbsp;mm and 2&nbsp;mm, there is also one of 0.35&nbsp;mm which is almost exactly 1 pica point. In other words, 2<sup>−1.5</sup> mm = {{frac|√8}} mm approximates an English typographic point rather well.