text: **Mark-to-Market Value**
  We record our derivatives using an estimated credit-adjusted, mark-to- 
  market valuation, 
  in accordance with IFRS. The estimated credit- 
  adjusted values of the derivatives are subject to changes in credit 
  spreads between us and our counterparties. The table below shows the 
  net asset of our derivative instruments at December 31, 2013: 
  **Adjusted Net Debt**
  We use adjusted net debt to conduct valuation-related analysis and 
  make capital structure related decisions. Adjusted net debt includes 
  long-term debt, net debt derivatives liabilities (assets), short-term 
  borrowings and cash and cash equivalents. 