The severity of a syslog message. The enumeration
values are equal to the values that syslog uses + 1.
For example, with syslog, emergency=0.
'emergency' : system is unusable
'alert' : action must be taken immediately
'critical' : critical conditions
'error' : error conditions
'warning' : warning conditions
'notice' : normal but significant condition
'informational': informational messages
'debug' : debug-level messages.