v.serialize_attribute("mpackage", to_mentity_ref(mpackage))
v.serialize_attribute("mgroup", to_mentity_ref(mgroup))
v.serialize_attribute("intro_mclasses", to_mentity_refs(sort_entities(intro_mclasses)))
v.serialize_attribute("mpackage", to_mentity_ref(mpackage))
v.serialize_attribute("mgroup", to_mentity_ref(mgroup))
v.serialize_attribute("intro_mclasses", to_mentity_refs(sort_entities(intro_mclasses)))