Symbol LS 5700 Product Reference Manual page 239

Parameter Menus
Decode Options
UPC/EAN Security Level
Level 3
If you have tried Security Level 2, and are still experiencing
misdecodes, select this security level. Be advised, selecting
this option is an extreme measure against mis-decoding
severely out of spec bar codes. Selection of this level
significantly impairs the decoding ability of the scanner. If
this level of security is necessary, you should try to improve
the quality of your bar codes.
UPC/EAN SECURITY LEVEL 3
5-175