In which scenario we will use this.
The below link will help:
Take a look here :
Missing Manual - Above() and Below()
You can use many scenarios, as such i will look this way
1) To get full accumulate data
2) Above most cases help us to identify from which row should start (Already link placed)
Rangesum(above()) generally we use for cumulative sum . Please find following snap for example.
refer the below link
Rangesum Above ,Below and Before,After and Range Avg
Retrieving data ...