When an object type on a higher meta level classifies an object type on a lower one, the link between them is generated as a material relation in the OntoUML output.

A classification link is not a material relation: it says that the lower-level type is an instance of the higher-level one. It should be generated as an instantiation link, which is currently not among the available relationship stereotypes.

Expected: classification links are recognised as such and labelled instantiation.