50 
 
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.  
We want to make add a new view as an additional sub-tab in the view that currently has the Annotations 
and Usage, tabs near the upper right corner8.  Once you are in the Individuals by class tab select 
Window>Views>Individual views>Individuals by type (inferred). This will give you a blue outline of the 
new view. As you move the outline around the existing window it will change depending how you move 
it, indicating how it will fit into the existing tab after you click. When the blue outline looks like figure 
5.2 click left and you will see the new view added as another sub-tab.  
After you click your UI should now look similar to figure 5.3. If you clicked somewhere else you can just 
go to the new view and delete it by clicking the X in the upper right corner of the view and then redo it 
and position it correctly. At first it may seem a bit unintuitive but after you do it a few times it becomes 
very easy to position new views.  
With this new view you can see the instances of each class displayed beneath the class. Each class can be 
expanded or contracted to view or hide its particular instances. Since we don’t have many instances in our 
ontology yet the usefulness of this new view isn’t that obvious but as we add more instances and as you 
deal with larger real ontologies in the future, this view can be very helpful to find specific instances of  a 
class. Note that the UI just shows the most direct class (or classes) that the Individual is an instance of. 
For example, we currently just have three individuals, the three instances of Spiciness: Hot, Medium, 
and Mild. These are also instances of owl:Thing (as are all instances) however the UI only displays 
them as instances of Spiciness since it is implicit that they are also instances of all the superclasses of 
Spiciness.   
 
 
8 Your particular Protégé UI may look slightly different than some of the screen snapshots depending on if your 
organization or another user has already customized the Protégé UI.  If you ever want to return a major tab to its 
default configuration select that tab and use Window>Reset selected tab to default configuration.