Identifies, by its numeric ID, which specific Virtual System the accompanying row of status data applies to. On a VSX gateway hosting many virtual systems, often for different customers or business units in a multi-tenant deployment, this ID is the key that lets an admin pull status for one specific tenant's firewall instance out of the shared table rather than the whole chassis. Example: filtering the status table on vsxStatusVSId = 3 isolates exactly the CPU, HA, and policy status for tenant 3's virtual firewall, without conflating it with other tenants sharing the same physical chassis.