Oracle Database Auditing: dba_audit_trail table

Hi,
from where i found the information about statementid,returncode of dba_audit_trail table.
These columns are populated in numbers.

Thanks
Asif Ghazi

<<UPDATE>>
Hi,

Oracle Database version is 11.2.0.3, and parameter audit_trail is set to DB, EXTENDED.

I execute two create table statements, one is successfully executed with RETURNCODE '0' (which mean successfully executed) but
other same create table query didn't perform because same table is already exists with RETURNCODE is '955'.

My question is, is there any list/table in Oracle database available for getting such information.

ACTION    STATEMENTID    RETURNCODE    ACTION_NAME    PRIV_USED              SQL_TEXT