Their respective quota might be allocated by transferring the appropriate amount of tokens via a smart contract-triggered transaction. This could also be extended towards other trading methods prevalent in the EU ETS, such as auctioning and OTC trading. Blockchain-based solutions for OTC trading have been proposed on the market to improve efficiency and lower transactions costs. This would also be the case for international emissions trading, linking different markets (e.g. between the EU ETS and the Swiss ETS) by eliminating many of the standardisation issues currently faced by ETS (e.g. registry designs, compliance periods), although some conceptual problems need to be addressed regardless of the technology used (e.g. nature of cap, offset provisions) (Kachi et al.,