If you are currently using MCOSYS and MCOUSR option, an enhancement to this option was added with APAR #: SO01359. This enhancement alters MCOSYS and MCOUSR to allow you to change only messages that currently have a certain severity level.
For example, suppress the messages CAY6079W (warning) and CAY6079I (informational). You will format your entry to:
Note that the old format of 079,-1 will still work which will suppress all severity encountered for CAY6079 message.