The amount of a provision should be the "best estimate" of the expenditure required to settle the obligation concerned. This estimate:

a. Should always be discounted to present value b. Should not be adjusted to reflect future events that may affect the amount of the required expenditure, whether or not those events are likely to occur c. Must always be made on the basis of advice from independent experts d. Should be the amount that would rationally be paid to settle or transfer the obligation