The Renewables Directive 2009/28/EC specifies that all producers of renewable power have a right to receive guarantees of origin for their renewable power production, on a request from the producer. The Norwegian Energy law § 4-3 states that Statnett has a duty to issue GOs.
NECS is the registry for GOs in Norway. GOs are issued based on meter values from the Norwegian balancing settlement.
Statnett is a member of the Association of Issuing Bodies (AIB). The AIB runs a communication Hub for transfers between the different registries. The standard European Energy Certificate System (EECS) is developed by AIB. Norwegian GOs follow the EECS standard.