oracle job type chain

1BEGIN
2  DBMS_SCHEDULER.CREATE_JOB (
3   job_name        => 'chain_job_1',
4   job_type        => 'CHAIN',
5   job_action      => 'my_chain1',
6   repeat_interval => 'freq=daily;byhour=13;byminute=0;bysecond=0',
7   enabled         => TRUE);
8END;