‹ OM-6.5 ATM Security Measures: Additional Measures for Retail Banks Sounders and Flashing Warning Lights › OM-6.5.1 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: April 2016 ‹ OM-6.5 ATM Security Measures: Additional Measures for Retail Banks Sounders and Flashing Warning Lights ›