Data sources contain data obtained with various result readers technologies, such as
        file sources, ascii extract, and readsim.
        
            Data sources are defined for the current study, not just for individual output
                responses. That is, Data Source 1 is accessible across all output response
                definitions.
        
        
            Tip: If the data source is retained, the array of data is stored for future
                use. If the data source is not retained, the array of data is discarded after the
                extractions are complete. It is recommended to retain the information unless disk
                space is a concern. To retain a data source, select its corresponding checkbox in
                the Retain column.