How is the foreign dividend adjustment amount (field/line 1K in worksheet -adjustment required for QD/LTCG) calculated?

Hello! I have an issue with form 1116 (foreign tax credit) and in particular with its worksheet. The foreign dividend I received in 2016 is reduced significantly by an adjustment amount (field/line 1K -adjustment required for QD/LTCG) calculated) How is this value in line 1K calculated?