While such restrictions on currency exchange have since become rare, savings are still available from back-to-back loans due to comparative advantage. The first formal currency swap, as opposed to the then used parallel loans structure, was transacted by Citicorp International Bank for a 10 year US Dollar Sterling swap between Mobil Oil Corporation and General Electric Corporation Ltd (UK). The concept of the interest rate swap was developed by the Citicorp International Swap unit but cross-currency interest rate swaps were introduced by the World Bank in 1981 to obtain Swiss francs and German marks by exchanging cash flows with IBM. This deal was brokered by Salomon Brothers with a notional amount of and a term of over ten years. During the global financial crisis of 2008, the currency swap transaction structure was used by the United States Federal Reserve System to establish central bank liquidity swaps. In these, the Federal Reserve and the central bank of a developed or stable emerging economy agree to exchange domestic currencies at the current prevailing market exchange rate & agree to reverse the swap at the same exchange rate at a fixed future date. The aim of central bank liquidity swaps is "to provide liquidity in U.S. dollars to overseas markets". While central bank liquidity swaps and currency swaps are structurally the same, currency swaps are commercial transactions driven by comparative advantage, while central bank liquidity swaps are emergency loans of US Dollars to overseas markets, and it is currently unknown whether or not they will be beneficial for the Dollar or the US in the long-term. The People's Republic of China has multiple year currency swap agreements of the Renminbi with Argentina, Belarus, Brazil, Hong Kong, Iceland, Indonesia, Malaysia, Russia, Singapore, South Korea, United Kingdom and Uzbekistan that perform a similar function to central bank liquidity swaps. South Korea and Indonesia signed a won-rupiah currency swap deal worth in October, 2013. The two nations can exchange up to 10.7 trillion won or 115 trillion rupiah for three years. The three-year currency swap could be renewed if both sides agree at the time of expiration. It is anticipated to promote bilateral trade and strengthen financial cooperation for the economic development of the two countries. The arrangement also ensures the settlement of trade in local currency between the two countries even in times of financial stress to support regional financial stability. As of 2013, South