|| Any piece of code or documentation, e.g. modeled classes, complete models, diagrams or programming code. Normally fits into a single file.
|| A classification of application domains within OOModels. In contrast to namespaces, there is only a single, global classification scheme. It helps to find information, because you can navigate through this scheme and search for artefacts by domain. It is, of course, somewhat deliberately and we have to agree upon this scheme to become useful.
|| A scope within which names are uniquely identifying something. In OOModels, there is a hierarchy of namespaces, very much like in Java or similar languages. Even more, OOModels namespaces follow the same conventions as in Java: the root of this hierarchy corresponds to reversly written domain names, they provide a natural way of being globally unique as well as defining unambigous ownership.