to 10 March 2006.) Versions and variants There are some main well-defined variants of the basic concepts, that are used as reference and as abbreviation to the W3C standards. HTML+RDFa RDFa was defined in 2008 with the "RDFa in XHTML: Syntax and Processing" Recommendation. Its first application was to be a module of XHTML. The HTML applications remained, "a collection of attributes and processing rules for extending XHTML to support RDF" expanded to HTML5, are now expressed in a specialized standard, the "HTML+RDFa" (the last is "HTML+RDFa 1.1 - Support for RDFa in HTML4 and HTML5"). RDFa 1.0 The "HTML+RDFa" syntax of 2008 was also termed "RDFa 1.0", so, there are no "RDFa Core 1.0" standard. In general this 2008's RDFa 1.0 is used with the old XHTML standards (as long as RDFa 1.1 is used with XHTML5 and HTML5). RDFa 1.1 Is the first generic (for HTML and XML) RDFa standard, now (2015) the "RDFa Core 1.1" is in the Third Edition. RDFa Lite RDFa Lite is a W3C Recommendation (1.0 and 1.1) since 2009, where it is described as follows: RDFa Lite is minimal subset of RDFa ... consisting of a few attributes that may be used to express machine-readable data in Web documents like HTML, SVG, and XML. While it is not a complete solution for advanced data markup tasks, it does work for most day-to-day needs and can be learned by most Web authors in a day. RDFa Lite consists of five attributes: vocab, typeof, property, resource, and prefix. RDFa 1.1 Lite is upwards compatible with RDFa 1.1. In 2009 the W3C was positioned to retain RDFa Lite as unique and definitive standard alternative to Microdata. The position was confirmed with the publication of the HTML5 Recommendation in 2014. Essence The essence of RDFa is to provide a set of attributes that can be used to carry metadata in an XML language (hence the 'a' in RDFa). These attributes are: a URI or CURIE specifying the resource the metadata is about and specifying a relationship and reverse-relationship with another resource, respectively , and specifying the partner resource specifying a property for the content of an element or the partner resource optional attribute that overrides the content of the element when using the property attribute optional attribute that specifies the datatype of text specified for use with the property attribute optional attribute that specifies the RDF type(s)