Start routines are used for mass processing of records. In start routine all the records of
DataPackage is available for processing. So we can process all these records together in start routine.
In one of scenario, we wanted to apply size % to the forecast data. For example if material M1 is forecasted to say 100 in May. Then after applying size %(Small 20%, Medium 40%, Large 20%, Extra Large 20%), we wanted to have 4 records against one single record that is coming in the info package. This is achieved in start routine.