A chain of custody (CoC) certification system tracks material arising in certified forests to the market place. It often covers the entire value chain from the forest, through manufacturing to the consumer, and it ensures that only certified products are able to be identified with an eco-label in the market place. CoC also ensures that material from controversial sources is not used in eco-labelled products. Conceptually, there are three principal CoC accounting options:
segregated wood flow, which physically segregates material originating in certified forests from uncertified material;
percentage mass of total wood flow, which transfers a percentage mass balance from certified and uncertified inputs to outputs; and
minimum threshold percentage of total wood flow, which permits certification of a total batch of products if the amount of certified material in the input batch exceeds a set minimum average threshold.