Miner-Activated Soft Fork (MASF)

A miner-activated soft fork, or MASF, is a method of deploying a backward-compatible Bitcoin rule change in which miners signal readiness in the blocks they mine, and the new rules lock in once signaling passes a threshold. Under the BIP 9 version-bits mechanism, activation requires 95 percent of blocks within a 2,016-block difficulty period to signal support.

Why it matters

The approach worked smoothly for upgrades such as CheckLockTimeVerify, but SegWit signaling stalled below threshold through 2016 and 2017 until pressure from a user-activated soft fork proposal, BIP 148, helped push it through. That episode reshaped views on how much say miners should have over protocol rules, and it demonstrated that bitcoin's rules are changed by broad coordination rather than by any single constituency, including the miners who secure the network. Gold's properties are fixed by physics; bitcoin's are fixed by consensus, and the SegWit fight is the key evidence cited that users, not industrial producers, hold final authority.

How it works

Miners set a designated bit in the block version field. Nodes count signals per retarget period, and when the threshold is met the deployment locks in, after which the new rules become enforced at a defined point. Signaling is meant as a coordination measure showing that upgraded hash power will enforce the rules, not a vote on the merits of the change.