The Symantec Backup Exec for Windows Servers Library Expansion Option enables you to use a robotic library with Backup Exec, which provides convenient, automated support for large capacity network environments. Support for a single robotic library drive is included with Backup Exec for Windows Servers. To obtain license keys for additional robotic library drives, you must purchase the Symantec Backup Exec for Windows Servers Library Expansion Option (LEO). This option allows concurrent processing on multi-drive robotic libraries.