A proposal was put forward that would have the same effect as adding mandatory empty blocks, where Proof-of-Work (PoW) targeted at 2 minutes would give a flag every 2 minutes and a block every 8 minutes. The conversion rate from hashing power to reward would be the same for both blocks and flags. However, a soft fork to add this rule would divert 20% of its hashing power to flag blocks, which would be ignored by legacy nodes, requiring the soft fork to win the race with 55% of the hashing power. This would mean that headers first clients would have to download more information to verify the longest chain, as they would miss 20% of the PoW if they only downloaded headers.