This indicates whether this pseudowire's MPLS-specific configuration row is stored volatile, non-volatile, or permanent, following the same StorageType convention as other Cisco MIBs, distinct from but paired with the base cpwVcStorageType in the parent table. It matters for change-control audits confirming that MPLS-specific parameters like EXP bits and TTL settings on a customer's VC will actually survive a router reload rather than reverting to defaults. If this is volatile while the base VC entry is nonvolatile, a reload could bring the pseudowire back up but with its EXP/TTL customizations silently lost.