of the subject or the partner resource (the resource that the metadata is about). Benefits There are five "principles of interoperable metadata" met by RDFa. Publisher Independence – each site can use its own standards Data Reuse – data are not duplicated. Separate XML and HTML sections are not required for the same content. Self Containment – the HTML and the RDF are separated Schema Modularity – the attributes are reusable Additionally RDFa may benefit web accessibility as more information is available to assistive technology. Usage There is a growing number of tools for better usage of RDFa vocabularies and RDFa annotation. HTML+RDFa statistics Simplified approaches to semantically annotate information items in webpages were greatly encouraged by the HTML+RDFa (released in 2008) and microformats (since ~2005) standards. these standards were encoding events, contact information, products, and so on. Despite the vCard semantics (only basic items of person and organization annotations) dominance, and some cloning of annotations along the same domain, the counting of webpages (URLs) and domains with annotations is an important statistical indicator for usage of semantically annotated information in the Web. The statistics of 2017 show that usage of HTML+RDFa is now less than that of Microformats. RDFa editors Web-based RDFa editors There are already a few RDFa editors available online. RDFaCE (RDFa Content Editor) is a WYSIWYM editor based on TinyMCE to support RDFa content authoring. It supports manual and semi-automatic generation of RDFa with the support of annotation services such as DBpedia Spotlight, OpenCalais, Alchemy API, among others. RDFaCE-Lite is a version of RDFaCE also supporting Microdata and available as a WordPress plugin. Desktop RDFa editors AutôMeta is an environment for semi-automatic (or automatic) annotation of documents for publishing on the Web using RDFa. It also includes a RDFa extraction tool to provide the user with a view of the annotated triples. It is available in both CLI and GUI interfaces. Examples The following is an example of adding Dublin Core metadata to an XML element in an XHTML file. Dublin Core data elements are data typically added to a book or article (title, author, subject etc.) <div xmlns:dc="http://purl.org/dc/elements/1.1/" about="http://www.example.com/books/wikinomics"> <span property="dc:title">Wikinomics</span> <span property="dc:creator">Don Tapscott</span> <span property="dc:date">2006-10-01</span> </div> Moreover, RDFa allows the passages and words within a text to be associated with semantic markup: <div xmlns:dc="http://purl.org/dc/elements/1.1/" about="http://www.example.com/books/wikinomics"> In his latest book <span property="dc:title">Wikinomics</span>, <span property="dc:creator">Don Tapscott</span> explains deep changes in technology, demographics and business. The book