(1) (source voltage) See Vcc.
(2) (Volume Shadow Copy Service, Volume Snapshot Service) A backup and restore function in Windows that makes copies of volumes (hard disks, etc.). VSS works stand alone within the OS; for example, starting with Windows Server 2003, it is used to create incremental backups of a volume. In Windows Server 2008, a diskshadow utility was added to allow VSS operations to be scripted. Also available in Windows client versions starting with Windows XP, VSS can be activated by third-party backup software and backup appliances. See snapshot.