What is a Rollover?
A Rollover is when a trader moves his position from the front month contract that is close to expiry to another contract further in the future. When rolling forward, a trader will close his current position and open a new position in the next/further contract months. In other words, it is the process of carrying forward an open position from one month to another month.
For example, Mr Jacob has a long position on 5 lots of NIFTY futures expiring in December. To roll over, he will simultaneously sell his 5 lots of December NIFTY futures and buy 5 lots of January/further NIFTY contracts.
Rolling over of contracts that are under a ban period is not permitted; you will ony be allowed to exit your existing (open) position.