You can display or hide display classes and area classes. In this method, you first assign objects (see "Creating Display Classes and Area Classes" ) to a display or an area class. Once defined, you can turn visibility on or off collectively for all the objects that belong to the class.

As you change the display of a class, you will notice that the status switches between on and off.

• On - Elements in the class appear in the model.
• Off - Elements in the class disappear from the model. They still exist; they are just hidden.