What is a Common?

A Common is the unit everyone in a Railroad Network community trades in. It is the same unit in every community, so that when communities eventually connect, a Common earned in one place means something in another.

It is mutual credit, not money

Nobody issues Commons. There is no treasury, no mint, and no way to create them out of nothing. A Common comes into existence only when one member pays another:

• Ana fixes Ben’s bicycle. Ben pays Ana 5 Commons.
• Ben’s balance goes from 0 to −5. Ana’s goes from 0 to +5.
• Add up every balance in the community and you get zero. Always.

A positive balance means the community owes you. A negative balance means you owe the community, in the form of goods or services someone will eventually buy from you. Both are normal. A community where everyone is at zero is a community where nobody is trading.

This is an old idea. Local Exchange Trading Systems have run this way in hundreds of communities since the 1980s. The software adds a tamper-evident history, a fraud-resistant way to confirm real-world trades, and the ability to keep going with no internet.

The debt floor

Because anyone can go negative, there has to be a limit. The debt floor is the lowest balance you may sign yourself down to. The default is −20 Commons. A payment that would take you below it is refused by the software before it ever reaches anyone.

The floor counts what has settled and what you have already signed but which has not settled yet, so you cannot get around it by sending several payments at once. It applies when you propose a payment and when you confirm a payment request someone sent you.

A community can set its own floor in the station’s configuration. The point is not to punish debt; it is to bound how much any one person can take out without giving back.

Fractions

Amounts are shown in Commons, with up to two decimal places (2.50 Commons). Under the hood the software only ever counts whole centicommons, one hundredth of a Common, so there is no rounding and no floating-point error in anything that gets signed.

What a Common is worth

Whatever the community decides, by trading. There is no exchange rate to any national currency and the software sets no prices. Communities tend to settle on a rough anchor in conversation (“about an hour of ordinary work”) and let the marketplace do the rest.