CombinedEntityClass

CombinedEntityClass[class1, class2, prop]

CombinedEntityClass[class1, class2, prop1 -> prop2]

CombinedEntityClass[class1, class2, {pspec a, pspec b, …}]

CombinedEntityClass[class1, class2, f]

CombinedEntityClass[class1, class2, spec, "jspec"]