Allows you to create a one-to-many join between the Master and Detail record sources This step only appears if you chose the Master/Detail type of data form.
Lists all available fields from the record source you specified in the Master Record Source step. Clicking a field highlights it and registers it as the linking field for this record source.
Lists all available fields from the record source you specified in the Detail Record Source step. Clicking the same field in this list highlights it and registers it as the linking field for the second record.