Models dialog
Used to create, manage, and switch between models in the open DGN file.
Each DGN file contains one or more models, each of which has its own set of eight views. You can create a model as a 2D or 3D Design type, as a 2D Drawing type or as a 2D or 3D Sheet type. Sheet models let you attach references to create a set of working drawings for the model file. Icons at the top of the Models dialog give you access to its various functions.