GD2 designates a coated secondary fibre board, insert and back grey
(chromo duplex board), top side wood-free white or slightly wood-containing white, with special volume (< 1.45 cm³/g, > 1.3 cm³/g).
Front top layer = hf or slightly hh white
Inlay = grey
Back cover layer = grey
hf white: wood-free white layer of bleached pulp with a maximum of 5% mechanical pulp
slightly hh white = slightly woody white layer of bleached pulp with a maximum of 30% mechanical pulp
grey = layer of recycled pulp (reused cellulose and groundwood fibres)