Oracle Database Discussions

When we are assign to a job to the auto task JOB Class on Oracle 10g scheduler, please advise what exactly we are asking Oracle to do?

From what I read from my text book, by assigning a job to a Job Class we can control the following..
Resource_Consumer_Group : Determine how much resources being allocate to the job
Logging_Level: Determine the detailing level of logging
Log_history: Determine how long the logged data should be retained

For auto task, what are the value on these paremeters set to?

Thanks,