This server hosts the syntax definitions for HTML 5, currently implemented in RelaxNG+Schematron. The original RelaxNG framework and Core modules were designed and written by fantasai. Henri Sivonen has add Web Forms 1 and 2 and HTML5 features. A web-based validation service using this schema is available.
Version control is provided at Bitbucket. A mailing list tracks changes to the code. Mercurial access is also available:
hg clone https://email@example.com/validator/syntax