The UML 2.5.1 specification says this about Node (p. 700, section 19.4.3 “Semantics”):

"(...) The internal structure of Nodes can only consist of other Nodes."

However, it doesn’t directly specify what Element can own a top-level Node in the model (as used on a deployment diagram, for example). Node inherits from Class as well as from the abstract type DeploymentTarget which inherits NamedElement.

Is it only Package that can own a Node that is not a nested Node? Or would other owner types be permissible?