UMLR — OCL and Text Mismatch

same_classifier
The classifier containing the referenced ConnectableElement must be the same classifier, or an ancestor, of the
classifier that contains the interaction enclosing this lifeline.
inv: represents.namespace->closure(namespace)->includes(interaction._'context')

The text says ancestor which has to do with Generalization issues... yet the OCL deals with namespaces... Ancestors can be in different namespaces... so which is it, does the interaction need to be in the namespace of the ancestor... or does the interaction need to be contained somewhere in the namespace hierarchy... I am thinking it is Generalization over namespace