[INVOICEUPSELLQTY1] - quantity of upsell item 1 (number can be between 1 to 20)
[INVOICEEXTRAITEM1] - value of extra invoice item 1 (number can be between 1 to 20)
[INVOICEEXTRAITEMNUM1] - as per [INVOICEUPSELL1] but the value is displayed with a decimal point and no thousands separator.
[INVOICEEXTRAITEMQTY1] - quantity of extra invoice item 1 (number can be between 1 to 20)
[INVOICETABLE] - invoice table