ConstReadonlyTRACE: 0Finest-grained diagnostic messages.
ReadonlyDEBUG: 1Debug-level messages for development.
ReadonlyINFO: 2General informational messages.
ReadonlyWARN: 3Warning conditions requiring attention.
ReadonlyERROR: 4Error conditions requiring immediate action.
ReadonlySILENT: 5No logging — suppresses all output.
Numeric log levels. Higher = more severe.