A defined benefit plan is a post-employment benefit plan other than a defined contribution plan.
The Group’s net obligation in respect of defined benefit plans is calculated separately for each
plan by estimating the amount of future benefit that employees have earned in return for their
service in the current and prior periods; that benefit is discounted to determine its present value.
The fair value of any plan assets is deducted. The Group determines the net interest expense
(income) on the net defined benefit liability (asset) for the period by applying the discount rate
used to measure the defined benefit obligation at the beginning of the annual period to the net
defined benefit liability (asset).