The Master Gate 
If you want to write simple log messages, use the method LogT().
All other output methods from the first type (with severity) are routed through this method to perform the logging.
The methods for location and category are the same as the first method type (xxxxxT()). The difference is in the additional severity argument:
Location
logT(int severity, String message)
logT(int severity, String subloc, String message)
logT(int severity, String message, Object[] args)
logT(int severity, String subloc, String message, Object[] args)
Category
logT(int severity, Location loc, String message)
logT(int severity, Location loc, String subloc, String message)
logT(int severity, Location loc, String message, Object[] args)
logT(int severity, Location loc, String subloc, String message, Object[] args)
Features
Recommendation
These output methods are outdated but not deprecated. You can use them at will.
We recommend that you use the new class com.sap.tc.logging.SimpleLogger.
More information: SimpleLogger Class