A namespace is a named element that can own other named elements. Each named element may be owned by at most one namespace. A namespace provides a means for identifying named elements by name. Named elements can be identified by name in a namespace either by being directly owned by the namespace or by being introduced into the namespace by other means e.g. importing or inheriting. Namespace is an abstract metaclass. A namespace can own constraints. The constraint does not necessarily apply to the namespace itself, but may also apply to elements in the namespace. A namespace has the ability to import either individial members or all members of a package, thereby making it possible to refer to those named elements without qualification in the importing namespace. In the case of conflicts, it is necessary to use qualified names or aliases to disambiguate the referenced elements.