Hey,

There are multiple parameters having specific points against each that is taken into consideration. These points are then clubbed.
Merit - divided into groups based on percentage
 80% above - 10 points
70% above - 8 points

Family income-  if you're from economically  weaker section then ypu surely have a edge over others.

Extra/ curriculum activities-  if you're part of it then you will awarded with some points over here.

Distance- if you're from far places like kashmir or north-east , you will be awarded some points.

These are clubbed and based on this the allotments are done.
Hope this helps!