Descoring caps with cap falling outside boundary?

Could you knock a cap off a post and then the cap fall outside the playing field, or is that illegal?

I don’t exactly know the rule, but intentionally knocking the cap of the post out of the field is illegal.

The rule is SG8


Just for reference, if it happens accidentally the cap is placed back in the field with the color of the opposite team that knocked the cap off up

ie red knocks out cap, cap is placed back by ref blue side up