User values must have a set function defined. Each parameter needs
a data type and a name. When you create a user value parameter, also set the
checkbox for a QofSetterFunc before clicking "Add this parameter".
All file values must also have a set function.
Calculated values (e.g. balances, totals or counts)
should not have a setter function.
Define your API later by revealing only those get and set
functions that you want to be part of the wider API. QOF uses static
functions wherever possible.
Feel free to experiment with the various options - if you need a new parameter
you can simply create an object with that single parameter and copy the code into
your existing object.