Viewer classes allow you to filter the data displayed in a world according to the identity of the user. You can expose a viewer class when you publish a world by making it public at runtime. As a result, your users can select the way they want to view your world.
For example, you might want to create a world that shows a series of blueprints for a building. However, the electrician, the plumber, and the city inspector might have different viewing needs. By creating three viewer classes to represent your three types of users and their data needs, you can include all the data in the world but filter out distracting or obscuring information for each user.
To create a viewer class, click Insert --> ViewerClass, type a name for the viewer class in the Viewer Class dialog box, and click OK.
The named viewer class is added to the Globals folder for the world. Every world has a default viewer class called Anonymous.
You can now use the new viewer class when writing an object property expression. For example, you might want to limit the visibility of an object to only one viewer class. In this case, you can use the IsViewer() function, which returns a Boolean result, and specify the named viewer class.
To use a viewer class to specify visibility, set the Visible property of the object to the following function expression, where viewer_class_name is the named viewer class you created previously:
=IsViewer(viewer_class_name)