... external entity in XML. parser—Software library in charge of reading and writing XML docu-ments.PI—Processing Instruction, a mechanism for including non -XML instruc-tions in an XML document.RDF—Resource ... XML. See also DOM.SGML—Standard Generalized Markup Language, the ancestor of bothHTML and XML. SOX—Schema for object-oriented XML, a proposed replacement for DTD.See also DCD, DDML, DTD, XML- Data, ... mechanism for establishing links in XML documents. XML eXtensible Markup Language, a new markup language published by the W3C to address the limitations of HTML. XML- Data—A proposed replacement for...