The output of DBMS_OUTPUT.PUT_LINE is not always visible, for example when SERVEROUTPUT is set to OFF.
Moreover, there is no standardized way to specify the importance of the message. It is better to use a logging mechanism instead.
Noncompliant code example
SET SERVEROUTPUT ON
BEGIN
DBMS_OUTPUT.PUT_LINE('An error occured'); -- Noncompliant
END;
/
