How to maintain the bonus register? What is the calculation of bonus?

All of you are requested to help me out to prepare the bonus registers:
How to maintain the bonus register? What is the calculation of bonus?
and other related things which are mandatory to enter in the register.

dearb vikas
in case of bonus your have to maintain four records.A and B register which is to be prepared by accounts dept or CA to see the set on/off.HR guyes can not prepare it because it has some technical terms of accounts to see how much profit/loss to see the % of bonus to be paid.
third one is C register which is to be prepared by HR and calculation is made as per percentage of bonus to be paid.
forth one is form D which is annual return to be submitted with labour dept.
tks
j s malik