Commons:An essay on the copyright status of IPAMonaPGothic, and its suitability for use in open source projects and on Wikimedia Commons

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This essay is written something like a mathematical proof for simplicity.


  • 2channel is a Japanese-language textboard which launched in May 1999.
    • After a domain seizure in 2014, two sites claim to be the "real" 2channel: and
  • The default font on the textboard and its direct predecessors[note 1] was, and on its successors is, MS PGothic (
    MS Pゴシック
    • This is because Internet Explorer 4 defaulted to this font for Japanese text.
  • The P stands for proportional.
  • In a traditional CJK[note 2] font, such as the regular MS Gothic (
    MS ゴシック
    ), a Latin character is equal to one half of a CJK character.[note 3]
  • In MS PGothic, however, the widths of Latin characters are more like a regular Latin font, such as Helvetica.
    • MS UI Gothic is similar, but narrower.
  • A font is metrically-compatible if it can be replaced in a document without changing the sizes of the glyphs, nor their offsets, nor their kerning.[note 4]
  • MS PGothic is a proprietary font.
  • Shift_JIS art is a form of digital art that relies on the metrics of MS PGothic to appear correctly.
  • A font metrically-compatible with MS PGothic can also be used to correctly view Shift_JIS art.

IPA Fonts[edit]

  • The Information-Technology Promotion Agency (IPA) (
    ) is an agency of the Japanese government.
  • The IPA distributes fonts (IPA Fonts /
    ).[primary 1]
  • The IPA Fonts are under the IPA Font License (IPAFL) (
    ), an OSI[note 6]-approved license.[primary 2]


  • When licenses conflict, the more strict license prevails, as long as all licenses allow sublicensing, and are compatible.
  • That is to say, a public domain file can become GPL without consent of the original author, but a GPL file cannot become public domain in the same way.
If a license is GPL-compatible, such as the Apache v2.0 license, for example, derivative works of it can be relicensed without knowledge or consent of original authors. [primary 3]
  • The IPAFL is a "viral" license like the GNU GPLv2,[primary 2] but is not itself GPL-compatible according to the FSF.[primary 3]

The Recipient may create, use, reproduce and/or Redistribute a Derived Program under the terms stated above for the Licensed Program.

Predecessors of IPAMonaPGothic[edit]

  • Mona (10 February 2001)[primary 4][primary 5] is an X11 (BDF) font metrically-compatible with MS PGothic.
    • License: Public domain. (Per README.ascii)
  • mona-outline (5 August 2003)[primary 6] is a TTF font metrically-compatible with MS PGothic.
    • License: Public domain. (Per README.ascii)
  • Sazanami (2004)[primary 7] is a pixel and outline font © 1990–2003 by Wada Laboratory, the University of Tokyo and © 2003–2004 Electronic Font Open Laboratory.
    • License: 3-clause BSD license. (Per README of sazanami-20040629)[note 7]


  • Jun Kobayashi modified the IPA Fonts, creating the IPA Mona Fonts
    .[primary 8]
    • He also, according to him, used parts of Sazanami fonts,[primary 7] and Mona.
  • Licenses conflict: 3-clause BSD, public domain, and IPAFL.
  • The 3-clause BSD license is IPAFL-compatible; it contains no provision that's impossible to meet under the IPAFL.
  • The IPAFL, therefore, prevails.
  • As a viral license, IPAMonaPGothic is also under the terms of the IPAFL.
  • IPAMonaPGothic is open source and suitable for use on Commons. QED


  1. Ayashii World and Amezou
  2. Chinese–Japanese–Korean
  3. For example, Q is equal to one half the width of ; so the width of QQ is equal to the width of .
  4. An example of three fonts that are metrically-compatible Helvetica, Arial and Arimo.
  5. Due to the larger character set of Shift_JIS, by definition, more can be expressed in it than can be in ASCII.
  6. en:Open Source Initiative
  7. Must open in EUC-JP encoding, e.g. with vim, :e ++enc=ujis. License is in English and matches exactly if you do that.

Primary sources[edit]

  1. IPAフォント(ver.003)
    : [1]
  2. a b IPA Font License (IPAFL): [2]
  3. a b Information about license compatibility is provided by the Free Software Foundation (FSF): [3]
  4. Official website in October 2001: [4]
  5. 2channel thread announcing v1: [5]
  6. monafont-ttf-2.30pre: [6]
  7. a b Sazanami fonts (29 June 2004): [7]
  8. IPA Mona Fonts: [8]