iCalendar Reference iCalendar data format for representing and exchanging calendaring and scheduling information
XPath 2.0 Reference the expression language behind XSLT 2.0 and XQuery for selecting nodes and computation
XPath 1.0 Reference language for addressing parts of XML documents in XSLT 1.0 providing as well basic facilities for manipulation of strings, numbers and booleans
SKOS Reference Simple Knowledge Organization System provides a model for thesauri, classification schemes, subject heading lists, taxonomies, ...
XSLT 1.0 Reference a language for transforming XML documents into other XML documents. (available in modern Web browsers)
vCard Reference representing and exchanging a variety of information about an individual
XML Sitemaps an easy way for webmasters to inform search engines about pages on their sites that are available for crawling
XHTML 1.0 Strict Reference a reformulation of HTML 4 as an XML 1.0 application with strict rules and without HTML 4.0 deprecated elements and attributes
Atom Reference an XML-based document format that describes lists of related information known as "feeds"