3. The apparatus of claim 2 , wherein the nested-structure, document-specific markup language is extensible markup language.
2. The apparatus of claim 1 , wherein, the document is expressed in a nested-structure, document-specific markup language and the query further comprises: links that are associated with join conditions that define relationships among the query nodes as being children, parents, ancestors or descendants of each other; and a query root node that represents answers to be returned.