This excerpt taken from the BP 6-K filed Sep 7, 2005.
Non-qualifying hedge derivatives
Under IAS 39, there are strict criteria that need to be met in order for hedge accounting to be applied. This adjustment records the impact of those derivatives, or elements thereof, held by the Group that do not qualify for hedge accounting, or hedges for which hedge accounting has not been claimed under IAS 39.
From January 1, 2005 these positions will be fair valued (marked to market) and the change in fair value taken to income.
Increase (decrease) in caption heading