cluster 

Indicates a single, alternative note head should be displayed instead of
individual note heads. The highest and lowest notes of the chord usually indicate the
upper and lower boundaries of the cluster note head.

Attribute Information

Used By

Attribute Group mei:mei_att.chord.vis.attribute.cluster

Source 

<xs:attribute name="cluster" type="mei:mei_data.CLUSTER">
  <xs:annotation>
    <xs:documentation>Indicates a single, alternative note head should be displayed instead of individual note heads. The highest and lowest notes of the chord usually indicate the upper and lower boundaries of the cluster note head.</xs:documentation>
  </xs:annotation>
</xs:attribute>

Sample