For example, Contract ABC,The contract term is 5 years. However, the billing report can be requested on any day e.g. Jan-2014 (01/01/2014-31/01/2014), Feb-2014(01/02/2014-28/02/2014), It also can be 01/03/2014-10/03/2014 (only 10 days billing report.). So I want to leave the billing START and...