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.