- 48 - © 2018 unitech Electronics Co., Ltd. All rights reserved.unitech is a registered trademark of unitech Electronics Co., Ltd.MS652 User’s Manual3.3.11 Code 39 Security Level3.3.12 Code 39 Reduced Quiet ZoneScan one of the following bar codes to enable or disable decoding Code 39bar codes with reduced quiet zones (the margins on either side of the barcode). If you select Enable, select a 1D Quiet Zone Level.Code 39 Security Level 0Code 39 Security Level 1*Code 39 Security Level 2Code 39 Security Level 3Enable Code 39 Reduced Quiet ZoneDisable Code 39 Reduced Quiet Zone*