CAD system, control method and control program for same

The present invention reduces the number of diagrams and the workload of management and the like, by aggregating spools of a common format, in plant design technology using a three-dimensional CAD system. Format specific data which is stored separately according to spool format is obtained by aggregating the respective spools in the internal data, which is generated by a data acquisition means, into respective common formats by a spool aggregation means. In this process, a comparison and classification means compares the contents of the control point tables relating to the respective spools, between each and every pair of the spools, so as to confirm whether there exist control point tables which are the same, with taking all of the start points of each spool as a point of origin, thereby determines whether both spools of each pair are matching based on prescribed common characteristics, as the result of this determination, in cases where both spools are matching, then creates format specific data which is stored separately with respect to each spool format.