Notification function called whenever an object derived from OdDbEntity is modified. 

The default implementation of this function does nothing. This function can be overridden in custom classes. 

This function is called whenever the following has occurred. 

1) The calling object is opened OdDb::kForWrite. 

2) One of its member functions either 

a Calls its assertWriteEnabled with recordModified == true. 

b Calls its recordGraphicsModified(true). 

3) The calling object is being closed. 

This function is called whenever the object as been modified. It therefore indicates only that the graphics for it may have changed.