This indicates the storage type of the conceptual row for a specific resource-owner threshold entry within a policy, where nonVolatile means that particular threshold configuration survives a reload. Because thresholds are configured per-row within a policy, one row per severity tier per resource owner, each threshold entry needs its own storage type set correctly, so a policy with multiple tiers could end up with some tiers persisting across reload and others silently reverting if this is set inconsistently. An admin who sets nonVolatile on the minor-tier threshold row but leaves the critical-tier row at its default volatile setting would find, after the next reload, that critical-tier alerting silently disappeared while minor-tier alerting remained intact.