You may not propagate, modify or sublicense the Program except as expressly provided under this License. Any attempt otherwise to propagate, modify or sublicense the Program is void, and any copyright holder may terminate your rights under this License at any time after having notified you of the violation by any reasonable means within 60 days of any occurrence. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as they remain in full compliance.