Immutable in Code
No admin function. Forking is the only path.
Problem
What does immutable mean in the context of the waterfall, and why does the distinction between "immutable on paper" and "immutable in code" matter?
Solution
No admin function. No governance call. Forking is the only path.
No admin function. No governance call. No timelock that, when expired, allows the ordering to be changed. The only path to changing the order is forking the chain — running incompatible node software on a different network with a different state root.
Discussion
The cost of forking is the cost of the credibility being abandoned. That is the point. "Immutable on paper" is a charter article that can be amended by the foundation. "Immutable in code" is a smart contract with no admin function that the protocol nodes refuse to deviate from.
Bitcoin's monetary policy is immutable in the same sense. There is no admin function on the supply curve. A hard fork could change it. A vote cannot. The 21M cap is the canonical example of this property in production for fifteen years.
See Also
- § 5.3 · What Governance Can and Cannot Touch — the rest of the immutable line
- § 5.4 · Narrow Surface Area — how the cookbook manages the risk of immutable code