Alertlog Error Filter in Oracle Cloud Control

ISSUE:
Some ORA- error in alert log file of oracle database instance is known and can be ignored for your system. You want to filter the error out so that no event will be generated when the error appears in the log

SOLUTION:
modify the filter expression
in all or any database instance target
Go to oracle database >monitoring> metric and collection setting>
Click edit for General Alter Log Error
change .*ORA-0*(54|1142|1146)\D.* to .*ORA-0*(54|1142|1146|???)(\D.*|$)

e. g.
to fileter ora-1234

new filter expression should be .*ORA-0*(54|1142|1146|1234)(\D.*|$)


reference:
http://docs.oracle.com/cd/E24628_01/em.121/e25160/osm_instance.htm
http://docs.oracle.com/cd/E24628_01/doc.121/e24473/toc.htm
http://docs.python.org/release/1.5.2p2/lib/re-syntax.html