Confusion over the standard of the three-unit A2, taken for the first time this summer, contributed to the grading crisis.
Original guidance was unclear about how the AS and A2 made up an A-level. It said the A2 should be judged above A-level. The AS-level is less demanding as students have only been studying for a year.
Schools, examiners and the exam board interpreted the advice differently.
As it defended its actions, the OCR board said it had rigorously applied an A2 standard that was higher than the A-level.
Submissions to the Tomlinson inquiry have asked for the AS and A2 qualifications to be separate, with the AS making up 40 per cent of the overall A-level.