From XML to UDL: a unified document language, supporting multiple markup languages

A proposal is made how to extend the XML node model in order to be compatible with JSON markup as well as XML markup. As XML processing technology (XPath, XQuery, XSLT, XProc) sees instances of the node model, but does not see syntax, it is thus enabled to handle JSON as well as XML. The extended node model is dubbed a Unified Document Language, as it defines the construction of documents from building blocks (nodes) which can be encoded in various markup languages (XML, JSON, HTML).