7. A data processing system comprising: a processor; and an accessible memory, the data processing system particularly configured to receive a document having fragments with attribute/value pairs; receive logical expressions that define relationships between fragments of the document; analyze the logical expressions to identify fragment names and attributes; create an index based on the analysis that includes names of the fragments to be candidates for selection into subdocuments; extract, from the document, all fragments named in the index; create, in the index, an entry for each attribute/value pair; create a plurality of subdocuments corresponding to the document, which includes finding top-level fragments in the index, finding second-level fragments related to each top-level fragment, and finding third-level fragments related to each second-level fragment; and store the subdocuments, including the respective related fragments.
7. A data processing system comprising: a processor; and an accessible memory, the data processing system particularly configured to receive a document having fragments with attribute/value pairs; receive logical expressions that define relationships between fragments of the document; analyze the logical expressions to identify fragment names and attributes; create an index based on the analysis that includes names of the fragments to be candidates for selection into subdocuments; extract, from the document, all fragments named in the index; create, in the index, an entry for each attribute/value pair; create a plurality of subdocuments corresponding to the document, which includes finding top-level fragments in the index, finding second-level fragments related to each top-level fragment, and finding third-level fragments related to each second-level fragment; and store the subdocuments, including the respective related fragments. 9. The data processing system of claim 7 , wherein extracting the named fragments includes parsing values of each attribute according to the logical expressions.