(1) Where the amount of the commission is not specified, the customary rate is to be deemed agreed.
(2) Commission is to be calculated on the basis of the remuneration payable by the third party or the trader. Discounts for cash payment are not to be deducted; the same applies to incidental costs, such as freight charges, packaging charges, customs duties and taxes, unless the incidental costs are charged separately to the third party. Turnover tax itemised separately on invoices solely by reason of tax law provisions are deemed not to be charged separately.
(3) In the case of fixed-term contracts on the cession of right to use and of fixed-term contracts for the transfer of use and enjoyment, the commission is to be calculated on the basis of the remuneration payable for the duration of the contract. In the case of contracts of indefinite duration, the commission is to be calculated on the basis of the remuneration payable until the earliest date when the third party may terminate the contract; if the contract continues, the commercial agent will be entitled to an additional commission calculated accordingly.