The emission right is the subjective right to emit one ton of carbon dioxide equivalent (CO2), from an installation or an aircraft that performs an aviation activity included in the scope of application of Ley 1/2005 (article 4) according to EU Reglamento 601/2012; and, for a specified period. The Basque Country is competent to review the Emissions Trading System (ETS) authorisation at least every five years and make the appropriate modifications.