are multifaceted in their attributes and interactions in the real economy. Several differences between centralised virtual currencies and crypto-currencies were identified in [@peters2014opening] and we briefly summarise some of these below:

-   In terms of changes to their specification. In centralised virtual currencies the specification can be altered by the controlling company, whereas in crypto-currencies the specification is agreed by cryptographic consensus.

-   In terms of their purpose and geographic area of operation, i.e. for use within an online community in the case of centralised virtual currencies, or in the wider economy, in the case of crypto-currencies.

-   In terms of the existence of a centralised authority to exert control over issuance, monetary policy and administration of currency balances. In centralised virtual currencies, a central authority can step in to control money supply and reverse transactions at will. In crypto-currencies, the absence of a centralised authority means that users control these aspects according to the computational power they contribute to the network. In addition, transactions are generally irreversible, as there is no authority to appeal to.

-   In terms of the flow of currency between users and the currencies’ exchangeability with fiat.

-   In terms of the value generation mechanism, 