A typed language for processing XML documents.

• XDuce uses regular expression types ( SchemaLanguageForXML ) to describe the languages an XDuce program is operating on. Regular expression types are equivalent to the full class of RegularTreeGrammar^? and is thus much more powerful than a grammar in DocumentTypeDefinition .
• XDuce has a powerful notion of subtyping. The question whether a certain tree is subtype A of a another three of type B is answered by comparing the regular expressions of the applied productions. This is an interesting approach for semi-structured data like XML because trees with additional (optional) content will be a subtype of a tree without the optional content.

-- MartinBravenboer - 29 May 2002