Angana, usually qualification codes are to determine the eligibility of each Candidate. Because it is difficult to manually keep a track of each Candidate's qualification, the codes have come in place. Now 01 is for those Candidates who are appearing for their 12th for the first time and 02 is for those Candidates who have completed their 12th. If you are appearing for improvement exams only for 1 subject, it means technically you have completed your 12th and your code should have been 02. But having said that, codes are only used for assessing the eligibility. But that doesn't determine your eligibility for counselling and admission. You cannot go back in time and correct it as the correction window has been closed. During the time of document verification, because you will be showing your original documents, nothing will go wrong.