Works are optionally identified by number and title. The work type also may indicate a link to the opus document that composes multiple scores into a collection.
<xs:complexType name="work"><xs:annotation><xs:documentation>Works are optionally identified by number and title. The work type also may indicate a link to the opus document that composes multiple scores into a collection.</xs:documentation></xs:annotation><xs:sequence><xs:element name="work-number" type="xs:string" minOccurs="0"/><xs:element name="work-title" type="xs:string" minOccurs="0"/><xs:element name="opus" type="opus" minOccurs="0"/></xs:sequence></xs:complexType>