I UNDERSTAND YOUR QUERY REGARDING THS as i would like to give you a brief about this as follows;

the special round is to be conducted after csab round as those who doesnot alloted with the seat in csab round and also i would like to give you the official article of career 360 regaeding this as follows;

https://engineering.careers360.com/articles/csab

the participation in cab is not directly done the dates are give specifically for it.if you still have any query ask me in comments.

best of luck!!