This indicates the storage type of the conceptual row for one specific resource-user-to-group membership entry, where nonVolatile preserves that particular member's group assignment across a reload. Because group membership is tracked per-member, each user's inclusion in a group is its own row, this storage type has to be set correctly on every membership row individually, not just on the group definition itself, or individual members can silently drop out of the group after a reload even while the group itself survives. A resource group that persists correctly across a reload could still lose one specific member process if that individual membership row was left at the default volatile storage type while the group's own row was set to nonVolatile.