Disclosed is a parametric feature-based 3D CAD system that allows multiple users to simultaneously edit a parametric feature-based 3D CAD model consisting of 3D parts and assemblies of those parts (3D Model). Several CAD users, each using their own computer, phone, or tablet, can edit the same 3D Model at the same time. Editing may be separate and simultaneous—there is no need for users to worry about locking, checking out, or otherwise restricting each other's access to 3D Models. Within each user's editing interface, the model may be presented in different representations, with edits to any representation applied and displayed across all representations.