text: Note that as with object properties defining a domain and/or range is optional. In general, it is a good 
  practice to do so as it can lead to finding errors in your ontology during the modeling phase rather than at 
  run time. 
  
  5.2 Customizing the Protégé User Interface 
  In order to demonstrate our new data property, we will need to create some instances of the Pizza class 
  and set the value of the data property hasCaloricContent. One of the advantages of Protégé is that it 
  is highly customizable to your specific requirements and work style. There are many views that are 
  available that aren’t included in the default Protégé environment because it would be too cluttered. In 
  addition, all of the views that you have already used can be resized, removed, or added to existing tabs. 
  You can also create completely new tabs of your own. 
  
  As an example, we are going to first bring up a new major tab called Individuals by class. This tab can be 
  useful to create individuals and to add or edit their object and data property values. We are going to 
  customize this tab to make it easier to use by adding a new view to it. 
  
  To begin use the menu option Window>Tabs>Individuals by class to bring up this new tab. Of course, if 
  it already exists in your UI simply select it. 