DocumentTypeDefinition was introduced in the XML standard as the schema language for XML. Because of the limited power of DTD and because it cannot handle XMLNamespaces in an acceptable way a lot of alternative schema languages have been developed. * [[XMLSchema]] * RelaxNG * DocumentStructureDescription (DSD). The schema languages that are currently used have been compared using a formal framework in TaxonomyOfXMLSchemaLanguagesUsingFormalLanguageTheory. -- Main.MartinBravenboer - 30 May 2002