官方文档：
http://tools.ietf.org/html/rfc5424
6. Syslog Message Format
6.2. HEADER
6.2.1. PRI
PRI=<Facility(0-23)*8+Severity(0-7)>
6.2.2. VERSION
6.2.3. TIMESTAMP
Example 1
1985-04-12T23:20:50.52Z
Example 2
1985-04-12T19:20:50.52-04:00
Example 3
2003-10-11T22:14:15.003Z
Example 4
2003-08-24T05:14:15.000003-07:00
6.2.4. HOSTNAME
6.2.5. APP-NAME
6.2.6. PROCID
6.2.7. MSGID
6.3. STRUCTURED-DATA
6.3.1. SD-ELEMENT
6.3.2. SD-ID
6.3.3. SD-PARAM
6.3.4. Change Control
6.3.5. Examples
Example 1 – Valid
[exampleSDID@32473 iut=”3″ eve