[4] [DFN[GitHub Flavored Markdown]] ([DFN[GFM]]) は、[[GitHub]]
で使われている [[Markdown]] の[[方言]]です。

[5] [[Markdown]] には色々な[[方言]]がありますが、
[[GFM]] はその中でも最大勢力です。そのため多くの実装が [[GFM]] 
対応を謳っていますが、独自の機能を追加していることも多く、
つまり [[GFM]] 自体にも多くの[[方言]]があります。

;; [[Markdown]] 参照。


[FIG(quote)[
[FIGCAPTION[
[1] [CITE[GitHub Flavored Markdown - User Documentation]]
([TIME[2015-03-21 10:49:18 +09:00]] 版)
<https://help.github.com/articles/github-flavored-markdown/>
]FIGCAPTION]

> GitHub uses "GitHub Flavored Markdown," or GFM, across the site--in issues, comments, and pull requests. It differs from standard Markdown (SM) in a few significant ways, and adds some additional functionality.

]FIG]


[2] [CITE[GitHub Help]]
([TIME[2016-07-12 23:42:32 +09:00]])
<https://help.github.com/categories/writing-on-github/>

[3] [CITE[Basic writing and formatting syntax - User Documentation]] ([TIME[2017-04-01 05:39:34 +09:00]]) <https://help.github.com/articles/basic-writing-and-formatting-syntax/>

[6] [CITE@en-us[A formal spec for GitHub Flavored Markdown | GitHub Engineering]]
([[Vicent Martí]]著, [TIME[2017-05-17 02:12:04 +09:00]])
<https://githubengineering.com/a-formal-spec-for-github-markdown/>

[9] [[CommonMark]] ベースに仕様変更。 [[GitHub]] の調査によると 1% 
が影響を受ける。 [[GitHub]] の[[データベース]]にあるものは書き換えて互換性を維持する。

;; [10] 1% ってかなりおおごとだけど、よくこんなことする気になったよなあ...

[7] [CITE[GitHub Flavored Markdown Spec]]
([TIME[2017-05-15 12:05:46 +09:00]])
<https://github.github.com/gfm/>

[FIG(quote)[
[FIGCAPTION[
[8] [CITE@en[github/cmark: GitHub's fork of cmark, a CommonMark parsing and rendering library and program in C]]
([TIME[2017-05-24 16:00:55 +09:00]])
<https://github.com/github/cmark/>
]FIGCAPTION]

> cmark-gfm is an extended version of the C reference implementation of CommonMark, a rationalized version of Markdown syntax with a spec. This repository adds GitHub Flavored Markdown extensions to the upstream implementation, as defined in the spec.

]FIG]


[11] [CITE@ja[氏せるぞぬの右脚botさんのツイート: "GFM、みなさん気付いてないかもしれませんがCommonMark準拠に再構成されたのでいろんな README.md がはめつしたし、GFMの中途半端なまねをしてきたいろんな処理系がいっしょに互換性を一気に消失してはめつしたぞ。"]]
([TIME[2017-05-24 15:49:34 +09:00]])
<https://twitter.com/tadsan/status/861158151491510273>

[12] [CITE@ja[Mooseさんのツイート: ". @github changed their Markdown parser and broke a lot of our documentation. Backwards compatibility, it matters."]]
([TIME[2017-05-24 16:25:37 +09:00]])
<https://twitter.com/mustpax/status/865406109523206144>

[13] [CITE@ja[Artem Zinnatullinさんのツイート: "Shame @github wasn't able to keep compatibility w/ #Headers in markdown for commits made before their md change. Lots prjcts have to fix it"]]
([TIME[2017-05-24 16:26:07 +09:00]])
<https://twitter.com/artem_zin/status/846103851933585411>

[14] [CITE@ja[Matt Brobergさんのツイート: "I had a markdown list rendering break and found this ~> A formal spec for GitHub Flavored Markdown https://t.co/cCtcY7Mqqy by @github"]]
([TIME[2017-05-24 16:27:10 +09:00]])
<https://twitter.com/mbbroberg/status/864222356021145602>

[15] [CITE@ja[Michael Berkowskiさんのツイート: "Did @github markdown change? Seeing lots of README files with unrendered: #Heading1 ##Heading2 ..now requiring whitespace # Heading1"]]
([TIME[2017-05-24 16:28:11 +09:00]])
<https://twitter.com/mberkowski/status/860528837926543360>

[16] [CITE@ja[Zev Eisenbergさんのツイート: "Did @github recently change the strictness of their Markdown’s header parser? I’ve seen a lot of “####Some Header” recently."]]
([TIME[2017-05-24 16:28:39 +09:00]])
<https://twitter.com/ZevEisenberg/status/854350219592577025>

[17] [CITE@ja[Alex Sorokoletovさんのツイート: "Hey, @github did you change markdown engine or rules? I literally see lots of repos with ### headers broken. I bet it wasn't like this b4"]]
([TIME[2017-05-24 16:28:54 +09:00]])
<https://twitter.com/AlexSorokoletov/status/850529454464131072>

[18] [CITE@ja[phnkさんのツイート: "Dear @GitHub – Did you change how GitHub Markdown syntax is parsed? Lists starting with 1. used to be numbered all the way, right? No more? https://t.co/oGXFc6YwSn"]]
([TIME[2017-05-24 16:29:35 +09:00]])
<https://twitter.com/phnk/status/846008012351377410>

[19] [CITE@en-us[A formal spec for GitHub Flavored Markdown | GitHub Engineering]]
([[Vicent Martí]]著, [TIME[2018-06-02 00:08:34 +09:00]])
<https://githubengineering.com/a-formal-spec-for-github-markdown/>

[20] [CITE[GitHub Flavored Markdown Spec]]
([TIME[2017-09-12 07:38:22 +09:00]])
<https://github.github.com/gfm/>

[21] [CITE[GitHub Flavored Markdown Spec]]
([TIME[2017-09-12 07:38:22 +09:00]])
<https://github.github.com/gfm/>

[22] [CITE[GitHub Flavored Markdown Spec]]
([TIME[2017-09-12 07:38:22 +09:00]])
<https://github.github.com/gfm/>

[23] [CITE@en-US[OpenRPC Specification | spec]]
([TIME[2020-06-25T22:22:13.000Z]], [TIME[2020-09-01T03:03:49.687Z]])
<https://spec.open-rpc.org/#rich-text-formatting>

[24] [CITE@en-US[Include diagrams in your Markdown files with Mermaid | The GitHub Blog]], [TIME[2022-02-16T11:48:39.000Z]] <https://github.blog/2022-02-14-include-diagrams-markdown-files-mermaid/>


[25] 
[CITE@en-US[Mermaid, topoJSON, geoJSON, and ASCII STL Diagrams Are Now Supported in Markdown and as Files | GitHub Changelog]], [TIME[2022-03-21T03:18:52.000Z]] <https://github.blog/changelog/2022-03-17-mermaid-topojson-geojson-and-ascii-stl-diagrams-are-now-supported-in-markdown-and-as-files/>

[26] [CITE@en-US[Render mathematical expressions in Markdown - The GitHub Blog]], [TIME[2023-07-25T09:31:49.000Z]] <https://github.blog/changelog/2022-05-19-render-mathematical-expressions-in-markdown/>

[27] 
[[JavaDoc]]