Materialien materiais material materialen materiales materiali materials materijali matériaux υλικά חומר The Materials hierarchy contains descriptors for a broad range of substances, from natural and synthetic raw materials to material products. Material products are included here rather than in the Objects facet because they can be used in the construction of various objects (e.g., plank for floors or walls), and because they are not necessary constituent parts of objects (e.g., shingle is not essential to roofs in the same way as roof ridges or eaves) (AAT)