This indicates whether this pseudowire's configuration is held only in volatile memory, in nonvolatile storage, or is permanently fixed, following the standard SNMP StorageType convention. A VC marked volatile will vanish on a device reboot or reload, silently taking down a customer's circuit unless it's also saved elsewhere. An engineer auditing why a pseudowire disappeared after a router reload would check that this had been left at volatile(2) rather than nonVolatile(3).