double 

If the double element is present, it indicates that the music is doubled one octave down from what is currently written (as is the case for mixed cello / bass parts in orchestral literature).

Element Information

Model

Source 

<xs:element name="double" type="empty" minOccurs="0">
  <xs:annotation>
    <xs:documentation>If the double element is present, it indicates that the music is doubled one octave down from what is currently written (as is the case for mixed cello / bass parts in orchestral literature).</xs:documentation>
  </xs:annotation>
</xs:element>

Sample