0Recordmode "Y" image purpose

Question

Hello all,
Could someone please help me with the following,
it was mentioned in some documentation that, update image u201CYu201D of 0RECORDMODE is used for roll-back and roll-forward. 
1.How exactly these roll-back and roll-forward are used, how it is accomplished
It was also mentioned that this roll-back and roll-forward is possible for key figures with maximum and min aggregation option only.
2.Maximum and minimum aggregation options are useful in BEx reporting, how come these are related to update type that too of 0RECORDMODE.
your invaluable responses would be appreciated with points

Answer 1

1.How exactly these roll-back and roll-forward are used, how it is accomplished
It was also mentioned that this roll-back and roll-forward is possible for key figures with maximum and min aggregation option only.
Imagine a case where selective deletion took place for a record in a ODS but the corresponding keyfigure is set to maximum aggregation. So now the maximum value has to be calculated from the remaining records. Hence the 'Y' field is used for rool-back and roll-forward.
2.Maximum and minimum aggregation options are useful in BEx reporting, how come these are related to update type that too of 0RECORDMODE.
Maximum and minimum aggregation are not just used in BEx. To ge to the reporting level, there are a lot of calculations and updates that take place in the dataflow. Hence in this case for example, if the keyfigure is employee count and aggregation is maximum; it is calculated at a prior step to reporting.