How does a non-mineable crypto-currency work?

Bitcoin depends on computer resources to add transactions to the blockchain (“mining”) and rewards these resources by issuing bitcoins.

XCP is non-mineable, so how does it ensure computer resources?

@nhoggard, Counterparty “lives” on top of the bitcoin blockchain.

All transactions are paid for to bitcoin miners, so while the number of Counterparty tokens is limited, mining and transactions “come from” Bitcoin.

Counterparty transactions = Bitcoin transactions with some extra data in them