text: 1 Pre-tax free cash flow is a Non-GAAP measure and should not be considered as a 
  substitute or alternative for GAAP measures. It is not a defined term under IFRS, and 
  does not have a standard meaning, so may not be a reliable way to compare us to 
  other companies. See “Non-GAAP Measures” for information about these measures, 
  including how we calculate them. 