Normally the discount is applied to the total price including any extra upsell items.
*If the code [roomonly] , is entered on a line then all phrases on that line apply the discount only to the room price.Example: [roomonly],Summer Offer
*If the code [extraonly] , is entered on a line then all phrases on that line apply the discount only to the extra items.[extraonly],Springspecial
The voucher discount is not applied to obligatory percent items.