16.3. SQL Grammar Extension for Autonomous Transactions
BEGIN [AUTONOMOUS] [TRANSACTION] [ ISOLATION LEVEL
isolation-level] END [AUTONOMOUS] [TRANSACTION]
isolation-level can be one of the following:
READ COMMITTED, or
AUTONOMOUS keyword is required to start an autonomous transaction, but can be omitted when completing an autonomous transaction. If you have several nested levels of autonomous transactions, they are completed one by one, starting from the innermost nesting level. The top-level transaction cannot be autonomous.