Understanding LOT=True Vs. LOT=False – Bitcoin Magazine

The discussion on Taproot activation appears to have reached its final stage, with the remaining decision revolving around the activation parameter LOT.

The code for Taproot, a proposed Bitcoin protocol upgrade for compact and privacy-preserving smart contracts, has been included in the most recent version of Bitcoin Core, currently the de-facto reference implementation for the Bitcoin protocol. The only remaining step is for the upgrade to activate on the Bitcoin network.

But as a consensus system without central authority, Bitcoin protocol upgrades can be challenging. If one segment of the network upgrades to a new version of the protocol before another segment does, different nodes might enforce different rules, introducing the risk that the network fractures between them.

A soft fork upgrade, which Taproot is, is backwards compatible to minimize this risk. As long as a majority of miners (by hash power) enforce the new rules, both upgraded and non-upgraded nodes accept their version of the blockchain: upgraded nodes because the new rules are properly enforced, and non-upgraded nodes because none of the legacy rules are being broken.

Several of Bitcoin’s previous soft forks have therefore been deployed by leveraging hash power as a coordination mechanism, which is referred to as a miner activated soft fork, or MASF. Once (usually) 95 percent of newly mined blocks included a bit that signaled readiness, all upgraded nodes would start enforcing the new rules. If this threshold wouldn’t be met within (usually) a year, the upgrade would instead expire.

In 2017, the Segregated Witness (SegWit) MASF got close to expiring; in the midst of a heated scaling debate, miners refused to signal readiness for the upgrade. In response, a grassroots group of users and some developers released a special Bitcoin software client: the BIP 148 client. The BIP 148 client would activate SegWit on a given date even if there was insufficient hash…

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