Transforming a source XML document satisfying a source DTD into a target
XML document satisfying a target DTD, transforming the source XML
document into a source document tree, where the source XML document
satisfies a first XML grammar and the source document tree satisfies a
second XML grammar; converting the source document tree into a target
document tree satisfying the second XML grammar; and transforming the
target document tree into the target XML document, wherein the target XML
document satisfies the first XML grammar.