Vmanage setting

[sukoo]

hi guy,
wish to check on some layman term for vmanage.
i notice the vmange come wif intake n exhuast setting.
and each group still got main n sub channal to on or off
so how should wi be choosing the setting?
wat is main n wat is sub?

hoped expert can help as i only to find discussion on it but no one mention on the setting for it
kekekekkekek