Model-based definition (
MBD), sometimes
digital product definition, is the practice of using
3D models (such as solid models, 3D
PMI and associated metadata) within 3D
CAD software to define (provide specifications for) individual components and product assemblies. The types of information included are
geometric dimensioning and tolerancing (GD&T), component level materials, assembly level
bills of materials, engineering configurations, design intent, etc. By contrast, other methodologies have historically required accompanying use of 2D
engineering drawings to provide such details.