Help for currencies / the money system:
The money system consists of currencies and denominations.
Different currencies can only be exchanged at a bank (for a fee) and vendors only use one currency. You can pay with any of the denominations of the vendor's currency though and you get change if needed. If you want to drop or give money to somebody you can only use the denominations which you really have though.
Each currency consists of its name, the plural name, a list of denominations and an exchange rate. By default a currency has a base denomination with the same name and the exchange rate factor 1.0. The exchange rate is the value of one unit of a denomination of a currency with factor 1.0. For example if the exchange rate of dollars is 1000 then 1 dollar is worth as much as an object with set_value(1000).
Each denomination consists of its name, the plural name to use, and an exchange rate factor relative to the base denomination of the currency (e.g. the base denomination has the factor 1.0). A denomination cent would have the factor 0.01 for example which means 1 cent is worth as much as an object with set_value(10) (if the exchange rate of dollars is 1000). Each denomination belongs to only one currency.
Currencies are administrated with admtool at daemons/currency.
When a new currency is created in admtool (by "add currency" or "add a denomination to a currency") the exchange rate is set to 1000. If "add currency" a base denomination is added. If you want to change some property of a denomination or the plural of a currency just add it again with the same name.