The HTML Working Group has published the First Public Working Draft of HTML+RDFa. RDFa is intended to solve the problem of machine-readable data in HTML documents. RDFa provides a set of HTML attributes to augment visual data with machine-readable hints. Using RDFa, authors may turn their existing human-visible text and links into machine-readable data without repeating content. This specification defines rules and guidelines for adapting the RDF in XHTML: Syntax and Processing (RDFa) specification for use in the HTML5 and XHTML5 members of the HTML family. The rules defined in this document not only apply to HTML5 documents in non-XML and XML mode, but also to HTML4 documents interpreted through the HTML5 parsing rules.