diagnose sys scanunit commands

Dear all, 

Would you please explain to me the below commands? What it does and when it will be used. 

I know it's an antivirus scan unit but what does it really do when enabled?

Current Firmware v7.2.2*

# diagnose sys scanunit stat

# diagnose sys scanunit bypass
enable             Enable bypass settings.
disable            Disable bypass settings.
show               Show bypass settings.
clear              Clear bypass settings.

# diagnose sys scanunit filter
list               Display the current filter.
clear              Clear the current filter.
negate             Negate the specified filter parameter.
vd                 Index of virtual domain. -1 matches all.