... of the data type you want to generate data for then click open. This will show you a message box with the path to the saved definition. Each data type in the tool exists in two parts. The definition and the item. The definition describes the general parameters of the type (e.g. name, default value, min, max, etc). The item is a single instantiation of that definition. The item contains the current editted values, children and various changeable parameters.