The default form and engineering numbering system for an object is determined by these relationships to the ClassDef; however, alternative specialized forms and engineering numbering systems can be configured via the classification tree.
When determining the form and the engineering numbering system for a classified object, the system looks up the classification tree for one that is related to both the node of the classification tree and the ClassDef to be created. If one is not found, the default form and engineering numbering system related to the ClassDef is used.