title: In MVVM model should the model implement INotifyPropertyChanged interface?
body: <p>I have clear idea about <code>View</code> and <code>ViewModel</code> in MVVM pattern. I am planning to implement MVVM pattern in my application. I'm facing an issue regarding the model. I have .xml file which is parsed and the information is displayed in the View.</p>
  
  <p>I need to be notified about the changes in the model for the first time only. From onwards on demand I need to be notified.</p>
  
  <p>So how to implement the model? </p>
  
  <p>Should I implement <code>INotifyPropertyChanged</code> interface in model class also? (I read that model should not implement <code>INotifyPropertyChanged</code> interface, since it is WPF specific)</p>