The credits, provided by the countries which have succeeded in emissions reduction to meet the allowance or by activities for emissions reduction, can be bought by the countries which have emitted the gases over the emissions allowance and are regarded as compliance with the emissions allowance.
排出量を排出枠内に抑えた国や事業で発生したクレジットを、排出枠を超えて排出してしまった国が買い取ることで、排出枠を遵守したと見做されるものである。