Allows a subobject of a complex object to notify its root object that it has been changed.

This function must be called within an subobject's close() method. 

The owner can then propagate the notification that it has been been modified. 

The default implementation of this function inform the database in which the owner resides has been modified; triggering any OdDbDatabaseReactors attached to it. This function can be overridden in custom classes. 

When overriding this function, it should: 

Here's how it's supposed to work: 

1) The subobject class's close() calls its triggers a "modified" notification which calls its xmitPropagateModify(). 2) The subobject class calls the its owner's recvPropagateModify() its object's pointer. 3) This owner's class's recvPropagateModify() sends a "modified" notification to the top of its class.