One of the aims of Naked Objects is to ensure that our domain objects are behaviourally-complete: that they encapsulate a coherent set of responsibilities. Not anaemic domain models, but OO like your mother taught you. So in this screencast we extend the example to add in various validation business rules for a property. We also specify whether the property is enabled, and even if it is visible.
http://danhaywood.com/2009/10/16/naked-objects-programming-property-business-rules/