Hi Udo, Yes, the basic idea is that a QCParentObject is an object that is owned by a parent. For instance if you have in your domain model a todo list that belongs to a project, the todo list items should be derived from QCParentObject. This also allows to delegate certain things back to the parent, like accessing the model, that is the root the object belongs to. Another example is for properties like “canEdit” where one can decide to have user rights only for the parent object (the project) and not for the child objects (the todo items). For practical purposes I usually create a domain model that is an artificial owner: the model that is the owner of all objects, thus resulting in all objects, except the modeli, to be a subtype of QCParentObject. But one could easily make a different implementation to link the objects back to the model (i.e. creating a subclass that returns for the model always the singleton of a certain class) I hope this rationale helps. Regards, Diego _______________________________________________ Magritte, Pier and Related Tools ... https://www.list.inf.unibe.ch/listinfo/smallwiki