MARC21       007k'05  Secondary support material
     Values: 
              #   No secondary support
              a   Canvas
              b   Bristol board
              c   Cardboard/illustration board
              d   Glass
              e   Synthetic
              f   Skin
              g   Textile
              h   Metal
              m   Mixed collection
              o   Paper
              p   Plaster
              q   Hardboard
              r   Porcelain
              s   Stone
              t   Wood
              u   Unknown
              z   Other