(1) The provision contained in section 452b (2) sentence 1 may be modified only by an agreement reached after detailed negotiations, whether for one or several similar contracts between the same parties. The other provisions of this Subdivision may be modified by contractual agreement only to the extent that the provisions referred to therein permit contractual modifications.
(2) In derogation from subsection (1), however, it may also be agreed by means of standard terms of contract that, in cases in which the place of damage is known (section 452a), liability will be governed by the provisions of Subdivision 1
1. irrespective of on which leg of carriage the damage occurs, or
2. if the damage occurs on a particular leg of carriage specified in the agreement.
(3) Agreements purporting to exclude the application of mandatory provisions of an international convention binding on the Federal Republic of Germany applicable to a leg of carriage are ineffective.