The European Commission recognises a number of voluntary schemes that demonstrate compliance with the sustainability criteria for biofuels. Schemes may adopt their verification procedures but must notify changes that might be relevant to the Commission, such as changes in auditing procedures. The Commission assesses the changes to establish whether the schemes still adequately cover the sustainability criteria. The scheme documents on this web site, however, are not updated in order to keep a reference to the status of the schemes at the time of their recognition; updated documents are available on the scheme websites linked above.