Creating a sidechain

Step 1: someone proposes it

A new sidechain starts as a proposal. A miner writes an M1M1 · Propose sidechainA coinbase message that proposes a new sidechain for a slot. message into the coinbase transactionCoinbase transactionThe first transaction in a block, written by the miner. BIP300 and BIP301 place the miners' messages and votes there. of a block they find. The message carries the sidechain's declaration and the slot it wants. A new proposal starts with zero votes.

Only miners write coinbase transactions, so a sidechain's developers ask miners to include their proposal.

Step 2: miners vote, block by block

In each later block, the miner can vote for the proposal with an M2M2 · ACK proposalA coinbase message in which a miner votes for a pending sidechain proposal. message that quotes the proposal's declaration hash. One block, at most one vote. A block that does not vote for it simply doesn't add one.

It is like a show of hands that lasts for weeks: every block is one hand, and only blocks that raise it count.

Step 3: activate or expire

The proposal activates when its votes go above the thresholdThresholdThe number of votes that must be exceeded, within a maximum age, for a proposal or withdrawal to pass. Betanet reports its own values. before it gets too old. If it runs out of time, it is dropped. Taking an empty slot needs fewer votes than replacing a sidechain that is already active: replacing one should be hard.