Assign the fields of the source and target data groups with the help of the arrow buttons,
the values of which will be written to the target data group when the data group action is run.
By clicking User-defined value, a fixed value will be defined that can be
written to a data field in the target data group each time the data group action is run. After you have defined the value in the following dialog,
assign the user-defined value to the required field of the target data group in the usual manner.
By clicking on Value from query, a data group can be filtered and the result applied to the target data field.
When a data fields of the type file is assigned to another data field of the type file, a value of a query or a value from the processing context,
the Edit icon is shown in the corresponding row of the field assignment. By clicking the icon a dialog is opened where the settings of the options for the saving of files can be defined.