mei:mei_model.layerPart.neumes_alternation

<xs:group name="mei_model.layerPart.neumes_alternation">
  <xs:choice>
    <xs:group ref="mei:mei_model.eventLike.neumes_alternation"/>
    <xs:group ref="mei:mei_model.syllableLike_alternation"/>
  </xs:choice>
</xs:group>