Electronic money system development in European Union by Daniel Wilusz is interesting:

Directive 2009/110/EC introduces quite liberal definition of electronic money which states that, “electronic money means electronically, including magnetically, stored monetary value as represented by a claim on the issuer which is issued on receipt of funds for the purpose of making payment transactions as defined in point 5 of Article 4 of Directive 2007/64/EC, and which is accepted by a natural or legal person other than the electronic money issuer.”

And than:

"From the technical point of view, this definition broadened the scope of electronic money systems architectures. Directive 2009/110/EC defines electronic money in the way that enables both token-based and account-based systems to operate, as it limits only the way the electronic money is stored (electronically or magnetically), without influencing the place of storage. In particular, European Authorities declare in the preamble of Directive 2009/110/EC that, “the definition of electronic money should cover electronic money whether it is held on a payment device in the electronic money holder’s possession or stored remotely at a server and managed by the electronic money holder through a specific account for electronic money.”

source: http://www.kti.ue.poznan.pl/sites/default/files/Wilusz_Legal_determinants_of_electronic_money_systems_development.pdf