16 Commitments and Contingencies Lease Commitments Property, plant and equipment includes $2 million as of December 31, 2015 (2014: $3 million) for capital leases and other beneficial rights of use, such as building rights and hire purchase agreements. Software includes $26 million (2014: $49 million) for assets acquired under non-cancellable software licenses. The financial obligations arising from these contractual agreements are reflected in long-term debt. Long-term operating lease commitments totaled $172 million as of December 31, 2015 (2014: $130 million). The long-term operating leases are mainly related to the rental of buildings and tools. These leases expire at various dates during the next 30 years. Future minimum lease payments under operating and capital leases are as follows: Operating Leases Capital Leases 2016 50 17 2017 37 15 2018 24  2019 18  2020 13  Thereafter 30  Total future minimum leases payments 172 32 Less: amount representing interest 1 Present value of future minimum lease payments 31 Rent expense amounted to $70 million in 2015 (2014: $63 million; 2013: $65 million). Purchase Commitments The Company maintains purchase commitments with certain suppliers, primarily for raw materials, semi finished goods and manufacturing services and for some non-production items. Purchase commitments for inventory materials are generally restricted to a forecasted time-horizon as mutually agreed upon between the parties. This forecasted time-horizon can vary for different suppliers. As of December 31, 2015, the Company had purchase commitments of $809 million, which are due through 2025. Litigation We are regularly involved as plaintiffs or defendants in claims and litigation relating to a variety of matters such as contractual disputes, personal injury claims, employee grievances and intellectual property litigation. In addition, our acquisitions, divestments and financial transactions sometimes result in, or are followed by, claims or litigation. Although the ultimate disposition of asserted cla