CAD system, CAD cooperative system, CAD data managing method, and storage medium

A CAD system and a CAD cooperative system maintain correspondence between a two-dimensional design plane and a three-dimensional design space (hereinafter referred to as a model), and between models for the same target. The correspondence between models is managed by an intra-model correspondence management unit, and the reference between models is managed by an inter-model reference management unit. Thus, there can be an interlocking operation between a two-dimensional design plane and a three-dimensional design space. furthermore, a three-dimensional reference can be automatically set for a three-dimensional design space to another model.