Zend_Log class defines the following priorities:
EMERG = 0; // Emergency: system is unusable
ALERT = 1; // Alert: action must be taken immediately
CRIT = 2; // Critical: critical conditions
ERR = 3; // Error: error conditions
WARN = 4; // Warning: warning conditions
NOTICE = 5; // Notice: normal but significant condition
INFO = 6; // Informational: informational messages
DEBUG = 7; // Debug: debug messages
These priorities are always available, and a convenience method of the same name is available for each one.
The priorities are not arbitrary. They come from the BSD syslog protocol,
which is described in RFC-3164.
The names and corresponding priority numbers are also
compatible with another PHP logging system,
which perhaps promotes interoperability between it and
Priority numbers descend in order of importance.
is the most important priority.
DEBUG (7) is the least
important priority of the built-in priorities. You may define priorities
of lower importance than
selecting the priority for your log message, be aware of this priority
hierarchy and choose appropriately.