Set the log level for the default context?

-- How do you set the logging level for the default context?

declare
  x PLOGPARAM.LOG_CTX;
begin
  dbms_output.put_line('Current Version = '||plog.getLOG4PLSQVersion); -- 4.0
  dbms_output.put_line('Current Level = '||plog.getLevel); -- 70

  --plog.setLevel(PLOG.LWARN); -- Why doesn't this line work?
                             -- If it did work, the next 2 plog lines should not get logged, right?
  plog.debug('Logging debug now.');
  plog.info('Logging info now.');
  plog.warn('Logging warn now.');
  plog.error('Logging error now.');
  plog.fatal('Logging fatal now.');

-- So I have to make a context (x) and pass it in always in order to change logging level?
  x := plog.init;
  plog.setLevel(x, PLOG.LWARN); -- next 2 plog lines will not get logged
  dbms_output.put_line('Current Level = '||plog.getLevel); -- 70
  dbms_output.put_line('Current Level (x) = '||plog.getLevel(x)); -- 40
  plog.debug(x,'Logging new debug now.');
  plog.info(x,'Logging new info now.');
  plog.warn(x,'Logging new warn now.');
  plog.error(x,'Logging new error now.');
  plog.fatal(x,'Logging new fatal now.');
end;