1. In Web Designer, locate the collection that contains the required data. As an example, for creation of new employees, look at the "Person" collection in the VI_Employee_Edit module.
2. Right-click the collection and select "Object in extension" --> "Modify property".
3. On the new node, set the base property to whatever property should be mandatory. Also, set the property "Minimum character count" to 1.
4. This change will make the property behave like a mandatory property for the selected collection.