The Wildcard Element Type which matches any elements presented in the data sources model.
Because generally we cannot say in advance which children and attributes a particular Element Type may have, in general case, the Wildcard Element Type has no children and no attributes.
However, the Wildcard Element Type can be casted to any other Element Type declared in the model, so as its further specific processing can be programmed.
Some DSM Types do allow to enumerate all children of an element even when its type is unknown. In that case, the Wildcard Element Type contains itself as a child and iterations by it (i.e. by all element's children) are always possible.