This provision does not imply a change in burden of proof.</p> <p> </p> <p>10.5. Siemens' obligation to fulfill an agreement is subject to the proviso that the fulfillment is not prevented by any impediments arising out of national and international foreign trade and customs requirements or any embargos or other sanctions.</p> 11. Supplementary Agreements, Place of Jurisdiction, Applicable Law <p>11.1. Any supplementary agreement requires the written form.</p> <p> </p> <p>