CommonMark

CommonMark is an attempt to produce a more standardized variant of Markdown, by a group that didn't include the creator of Markdown, John Gruber, who objected to the original name of this variant ("Standard Markdown"), so it was renamed first "Common Markdown", and then CommonMark.

The IANA classifies CommonMark as a "variant" of Markdown. Its registered variant identifier is "CommonMark".

Github flavored Markdown is based on the CommonMark spec, but with a few extensions.

Specs

 * Official spec

Software

 * commonmarker: Ruby implementation of CommonMark spec

Other links

 * Official site
 * Tutorial
 * Standard Flavored Markdown
 * Standard Markdown is now Common Markdown
 * CommonMark and the Future of Scholarly Markdown
 * Markdown throwdown: what happens when FOSS software gets corporate backing?
 * CommonMark and the Future of Scholarly Markdown
 * RFC 7764: Guidance on Markdown
 * CommonMark Markdown variant registration