The standard format for NIOS and British curriculum are as follows:
For British IGCSE:
Students in the 10th grade have their board exams with one term, one mock(pre-board), and two boards at the center.
Students in the 9th grade have internal assessments and two term exams.
Students in the 11th grade, AS level have exams at school, mock exams, and then final at center.
Students in the 12th grade, A level have mock exams, and then final at center.
For NIOS:
Students in the 10th grade have their board exams with one term, one mock(pre-board), and two boards at the center.