The Priority value is calculated by first multiplying the Facility number by 8 and then adding the numerical value of the Severity. For example, a kernel message (Facility=0) with a Severity of Emergency (Severity=0) would have a Priority value of 0. Also, a "local use 4" message (Facility=20) with a Severity of Notice (Severity=5) would have a Priority value of 165. In the PRI of a syslog message, these values would be placed between the angle brackets as <0> and <165> respectively. The only time a value of "0" follows the "<" is for the Priority value of "0". Otherwise, leading "0"s MUST NOT be used. – RFC 5424, Section 6.2.1
| Severity ➡️ | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|---|
| Facilities |
||||||||
| kernel (0) | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| user (1) | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| mail (2) | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 |
| system (3) | 24 | 25 | 26 | 27 | 28 | 29 | 30 |