BIP 8 — Version bits with lock-in by height

BIP 8 (Version bits with lock-in by height) is an alternative soft-fork deployment method to BIP 9. It measures signaling periods by block height rather than timestamps and adds a 'lockinontimeout' (LOT) parameter that can guarantee activation at the end of the deployment window even without miner supermajority signaling. Repository status: Draft (Informational).

Debate relevance: Central to activation-method debates, especially the LOT=true vs LOT=false argument from the Taproot activation period (2020-2021). Invoked whenever someone argues miners should not hold effective veto power over soft forks. Common misstatements: "Taproot activated via BIP 8" — Bitcoin Core's Taproot deployment used the 'Speedy Trial' approach, a modified version-bits deployment, not BIP 8 as written. BIP 8 remains a Draft that has not been used unmodified for a mainnet activation.