Description: Severity of the alert. The enumeration is borrowed from Common Information Model (CIM): 0 - fatal: indicates an error occurred, but it's too late to take any actions; 1 - critical: an action is needed immediately and scope of the error is broad; 2 - major: an action is needed, the situation is serious; 3 - minor: an action is needed, but the situation is not serious; 4 - degraded/warning: the user decides whether to take an action; 5 - informational: indicates state change or status change, but it's not an error; 6 - debug: information that are logged for later analysis.