A synonym search section searches a synonym dictionary for synonym group
identifiers indicating synonym groups to which tags included in first
structure-designating information from a terminal belong. Based on a
search result, a structure-designating-information generation section
generates second structure-designating information in which the tags
included in the first structure-designating information are replaced with
the respective synonym group identifiers indicating the synonym groups. A
synonym-structure-template search section searches a
synonym-structure-template management block for a synonym structure
template that matches the second structure-designating information. An
acquisition section acquires, from a database, a document structure in a
structured document indicated by a structure template corresponding to
the detected synonym structure template.