qt - Double spending from "green addresses" & mitigation

Double spending from "green addresses" & mitigation: Suppose a user pays for a service (service1) using a "green...

If service1 trusts service0's green address implicitly, it can send the coins immediately; there is no advantage to waiting. The recipient can then decides how many blocks to wait for before treating the payment as confirmed. If service0's green address isn't trusted, service1 needs to take into account that if service0 double-spends, service1 will be liable for the reversed transaction to service2. He can remedy it by resending with different coins, but it still won't look good. The inputs of a transaction can reference outputs of transactions in the same block. So the block will include (interspersed with other transactions) a sequence of transactions where each one references the previous one. As far as I know, no. An input can only reference the output of a previous transaction, where "previous" is either in a previous block or an earlier (in listing order) transaction...

Full article: http://bitcoin.stackexchange.com/questions/5946/double-sp...