The principal legal provisions are Articles 107 to 109 TFEU. The specific rules and their interpretation are established by secondary legislation – Frameworks, Directives, Regulations, Communications and Guidelines – and by EU case law. Member States are required to notify the Commission of any plan to grant or alter state aid unless it is of a type covered by the General Block Exemption Regulation (e.g. investment and employment aid to SMEs). The Commission then decides on the legality of state aid: it can monitor, verify, restrict and recover any forms and levels of aid and must approve aid grants before they can be implemented.