Example :
<!-- 1x1 GENERIC INDUSTRIAL/MODERN -->
<ArtRef Name="generic:mod_eu.nif::1x1_03">
<Attribute Class="Era">ERA_MODERN</Attribute>
<Attribute Class="ArtStyle">ARTSTYLE_ANGLO_AMERICA,ARTSTYLE_NORSE,ARTSTYLE_EUROPE,ARTSTYLE_NATIVE_AMERICA,ARTSTYLE_BARBARIAN</Attribute>...