A coin's terms decide what everyone in it pays and receives. On fix they are part of the coin.
When a coin is created, the current config is copied into its own market account:
the fee rate on the curve and the fee rate in the pool;
how each fee splits between the protocol, the creator, the pool and a call slice;
the total supply and its decimals;
the curve's virtual reserves and the tokens it sells;
the bounds on a call's horizon and the length of its scoring window.
Creation checks that the creator saw this exact version. If the config changed between the preview and the transaction, creation stops, and the creator sees the new terms first.
From then on, nothing changes them for that coin.
why they can't move
Chris Dixon's platform cycle runs on one ability: changing the terms after people have committed. A coin whose terms are written into it gives that ability nowhere to act.
Nick Szabo pointed at the same weak spot from the other side: a root administrator who can alter anything grows more fragile as strangers and value accumulate.
In one case Mert described, a loss came down to one admin key in the hands of a former employee.
Keys don't have to be ours to reach a coin. A coin that trades on another platform's AMM also answers to that platform's keys and config. On fix the curve and the pool are the same program, so the terms written into the coin are the only terms that apply.
Terms kept off the page are the same problem in another form. ZachXBT pointed to a project whose deck promised fairness and transparency while its KOL vesting terms appeared nowhere in its docs.
the config
The config is a template for coins that don't exist yet. A change to it shapes the next coin and never one already trading.
Vitalik Buterin's fourth test for a credibly neutral mechanism is that it shouldn't change often, because each change lets whoever makes it aim at people whose positions are already known. A config change on fix reaches only coins whose holders don't exist yet, so it has no one to aim at.
The config can pause new coins. A pause stops creation only, and every coin already made keeps trading.
No instruction reaches a live coin's market, its fees or its funds. Handing the admin role to someone else can't reassign a coin's creator or unlock anyone's money.
The program's source is public, so anyone can read for themselves what the config can and can't reach.
There are no case-by-case exceptions. Vitalik Buterin's case for hard rules over judgment calls is that judgment can be argued into anything. No one at fix decides, coin by coin, what is allowed.
without us
A coin doesn't need us once it exists. Trading needs no keeper. Anyone can checkpoint a call's window and anyone can settle it, and our keepers only do it on time as a convenience.
That is the test Vitalik Buterin set for applications: they should keep working after their developers are gone.
A holder trades under the terms the coin was born with, from its first trade to its last.