Money has four functions:
- unit of account
- medium of exchange - the only function healthy buying infrastructure might augment or even obsolete (in the Consumerium Credit type of vision)
- standard of deferred payment
- store of value
Understanding all four makes it easier to design a self-funding system - that is, one that takes in as much cashflow as it uses. Knowing when or for what reason people entrust money to a system requires the analysis above. Details relevant to Consumerium should be at financial capital since there are financial capital instruments that serve one, two or three of the above functions without actually serving all four and thus becoming "money".
See w:money for a more detailed discussion.