In the absence of a spec, early implementers consulted the original Markdown.pl code to resolve these ambiguities. But Markdown.pl was quite buggy, and gave manifestly bad results in many cases, so it was not a satisfactory replacement for a spec. Markdown.pl was last updated December 17th, 2004.
Because there is no unambiguous spec, implementations have diverged considerably over the last 10 years. As a result, users are often surprised to find that a document that renders one way on one system (say, a GitHub wiki) renders differently on another (say, converting to docbook using Pandoc). To make matters worse, because nothing in Markdown counts as a “syntax error,” the divergence often isn’t discovered right away.
, which compares the output of 20+ implementations of Markdown against each other to see if a consensus emerges.
We propose a standard, unambiguous syntax specification for Markdown, along with a suite of comprehensive tests to validate Markdown implementations against this specification. We believe this is necessary, even essential, for the future of Markdown.
That’s what we call CommonMark.
Who are you today?
We’re a group of Markdown fans continually working toward the vision of CommonMark — a standard, interoperable and testable version of Markdown.
We’re a group of Markdown fans who either work at companies with industrial scale deployments of Markdown, have written Markdown parsers, have extensive experience supporting Markdown with end users – or all of the above.
John MacFarlane, of Pandoc
David Greenspan, of Meteor
Vicent Marti, of GitHub
Neil Williams, of Reddit
Benjamin Dumke-von der Ehe, of Stack Overflow / Stack Exchange