AutoCAD Utility Design drawings are regular DWG files that contain an industry model. The industry model defines the underlying set of feature classes and associated attributes of the design features you create.
Feature classes are groups of features, such as conductors, transformers, and poles, each of which have attributes, such as model name, voltage, phase, or owner. The Model Viewer palette in the Design Explorer can display all the feature classes available in the industry model or just those in use in your drawing.
Your industry model can be configured with feature classes and attributes appropriate to your work.
The Model Viewer tab on the Design Explorer lists all the feature classes in the industry model in your design drawing.