JBoss ON expects log messages to follow the log4j log pattern, over all.
date severity [class] message
The date format is configurable when event monitoring is enabled. For custom logs, a custom pattern can be added. If no date format is given, then the three standard formats used by log4j are tried.
dd MM yyyy HH:mm:ss,SSS
The severity must be next. It can be plain, surrounded by brackets, or surrounded by parentheses.
date SEVERITY [org.foo.bar] my message
date [SEVERITY] [org.foo.bar] my message
date ( SEVERITY ) [org.foo.bar] my message
After the severity, there are no real constraints on the format of the log entry. If classes or other identifiers are passed, they are properly displayed.