G-7510: Always prefix ORACLE supplied packages with owner schema name.
Major
Security
Reason
The signature of oracle-supplied packages is well known and therefore it is quite easy to provide packages with the same name as those from oracle doing something completely different without you noticing it.
Example (bad)
DECLARE
co_hello_world CONSTANT STRING(30 CHAR) := 'Hello World';
BEGIN
dbms_output.put_line(co_hello_world);
END;
/
Example (good)
DECLARE
co_hello_world CONSTANT STRING(30 CHAR) := 'Hello World';
BEGIN
sys.dbms_output.put_line(co_hello_world);
END;
/