In F5 TMOS, a User Configuration Set (UCS) is the standard archive format used for backing up and migrating a complete system configuration .
Composition: A UCS file contains all necessary configuration data, including system-specific files, license information, SSL certificates, private keys, and local user accounts.
Procedural Use: When migrating to new hardware or performing an RMA replacement, the UCS file is the primary tool used to restore the entire Control Plane state to the new device.
Restoration: It can be managed through the Configuration Utility under System > Archives or via the CLI using the tmsh load /sys ucs command