According to Reflector;), INotifyPropertyChanging is used in Linq to SQL and its third-party counterparts (for example, Devart.Data.Linq) to optimize tracking changes in entities (delaying the snapshot of an object until the first change).
, X, DataContext X- ( ), INotifyPropertyChanging.
INotifyPropertyChanging X PropertyChangingEventHandlers. , DataContext .
, INotifyPropertyChanging , DataContext (Linq to Sql), .
INotifyPropertyChanging Weaver;)