‹ OM-5.4 ATM Security Measures: Additional Measures for Retail Banks Sounders and Flashing Warning Lights › OM-5.4.1 Banks may ensure the adequacy and effectiveness of external security measures throughout the ATM environment through the additional security measures outlined in this Section. Added: January 2020 ‹ OM-5.4 ATM Security Measures: Additional Measures for Retail Banks Sounders and Flashing Warning Lights ›