Syntax is:

    <View Type="Instanced" Title="Global Constants">
      <InstancedAttributes>
        <Att Name="physics" Type="physics" />
        <Att Name="physical-constants" Type="physical-constants">
          <ItemViews>
            <View Item="absolute-zero" Type="Default" ReadOnly="true"/>
          </ItemViews>
        </Att>
      </InstancedAttributes>
    </View>