Choose 'All volumes' so that the macro scans all mounted volumes, including all networked volumes and volumes that don't appear in the Mounted Volumes Area.
Choose 'All local volumes' so that the macro scans all mounted volumes that are "local" to the host computer. Those volumes across a network, for example, will not be scanned.
Choose 'All selected volumes' so that the macro scans all selected volumes in the Mounted Volumes Area.
Choose 'System volume only' so that the macro scans only the volume with the active system file.
