In general factoring concept is used to reduction of salary wrt o absence record.
How it works is find out reduction factors wrt Hours, Working days, Calendar days, for all the logic is same.
Let say absence days are 15 now system brings reduction factor wrt following calculation.
Number of working days - Absence days = 30 planned working days - absence days 15 = 15/30(Number of planned working days) = 0.5
Monthly salary is 10000, after 15 days absence days salary is 10000*0.5 = 5000.
This is called as factoring same is been incorporated in the factoring sub schema schema, Payroll schema.
Hope you understand explore system same you can find out.
Regards
Venkatesh