Both your internal assessment rank and mark are submitted to the board of studies, so they know how you performed in relation to the other kids in the class.
then there is no difference in one student getting 30% and is coming 1st in a subject at one school and one student getting 90% and is coming 1st in the same subject at another school.
they submit your total assessment mark to one whole number
The BOS then moderate that mark against the exam marks to finalise your mark using the relative gaps between the ranks as well as the ranks based on the school based assessment mark.