Scan direction option off in crt-beam-simulator

Hello

Can anyone explain what does scan direction off option does in crt-beam-simulator. This option solves annoying banding that is slowly moving and that is great.

In blurbusters original faq prefered and recommended option is 1, what else is removed or disabled when turning this option off? Blur reduction seems similar.

I tried searching for answer online but no luck.

Thanks