Meter operates on epochs, which are signaled by k-blocks (regular blocks are called m-blocks). At the end of epoch, the committee nodes vote on the longest PoW chain and distribute mining rewards to all the PoW miners, it also pass the information to the PoW chain and all the PoW miners will have to start mining for the stamped PoW block. To create a k-block, the PoW chain typically has to have more than 60 blocks. Since the average PoW block period is 1 minute, each epoch is therefore around 1 hour (currently the time for epoch is completely decided by PoW, but we will implement cross interactions for epoch adjustments in the future). All system financial related activities like reward distribution, entering and exiting the delegate node pool only happen at k-blocks.