This interface extends LayoutFormatter, adding the capability of taking and additional parameter. Such a parameter is specified in the layout file by the following construct: \format[MyFormatter(argument){\field} If and only if MyFormatter is a class that implements ParamLayoutFormatter, it will be set up with the argument given in the parenthesis by way of the method setArgument(String). If no argument is given, the formatter will be invoked without the setArgument() method being called first.