oNVDL is the oXygen XML Editor NVDL implementation. It was developed on top of Jing to add NVDL support starting from the existing NRL support. It also adds a couple of fixes to Jing related with XML Schema validation. oNVDL is included in the XML editor, but is available also as a separate file download.
NVDL stands for Namespace-based Validation Dispatching Language and it is Part 4 of ISO/IEC 19757 DSDL (Document Schema Definition Languages). It allows specifying sections of XML documents to be validated against different schemas thus enabling the creation of complex documents containing multiple languages without the need to modify the schemas that define each language to take into account the other languages. It allows also mixing different schema types like XML Schema, Relax NG and Schematron. A typical example is a document that contains XForms content inside XHTML.