(3)To ensure consistency with accounting practices, institutions should use the last available accounting value of a non-trading book position as a basis for calculating the own funds requirement for foreign exchange risk in accordance with the alternative standardised approach. However, the fair value of those positions is also deemed an appropriate basis for the calculation of the own funds requirements. Therefore, institutions should be allowed to use the fair value instead of the last available accounting value as a basis for that calculation if they measure all their non-trading book positions at fair value at least quarterly.