Hi Jayashree,
Every Key Figure has a base planning level. Example SalesForecastQuantity is by Period,Product Customer. You can plan at any level for SalesForecastQuantity, ie Product/Customer level or ProductFamily/CustomerGroup Level. The data then gets proportionally disaggregated and stored at this base planning level.
There are some KeyFigures where the base planning level is at higher hierarchy Level. For example in standard delivered model, you can see FinancePlanQty is at ProductFamily/CustomerRegion level. The data is always stored at this level and does not disaggregate to Product/Customer.
Your base planning level of the key figure defines what level data is stored.
For certain key figures, the base plan level may be different . eg Demand by Location or Dependent Demand Quantity is by Product/Location . You would define a calculation using Customer Sourcing Ratio along with Consensus Demand to calculate this KeyFigure.
All these are Standard examples in S&OP Training and S&OP delivered models. You can look at the key figures base planning level and calculation chain to understand how it works.
Hope this helps.
Thanks,
Raghav