# Using Properties to Dynamically Create a UI

The real power of setting custom properties is when you are using them to drive runtime behavior. A typical situation might be when you are laying out a presentation space and want to use a mask (or picture string). For example, to define properties for a string that represents a social security number, you could create a Property Name of SSN-MASK with a Property Value of `000-00-0000`. At runtime you could evaluate the property name and apply the proper formatting when appropriate.