Hi SCN,
As i already mentioned earlier, what you are seeing in planning table /n/sapapo/sdp94 is based on what characteristics and key figures you have selected in data view. So once you are in interactive planning you select the data view to let the system know what key figures and characteristics to display.
Now key figures are storage containers, which are storing data in a fact table (key figures) against dimension tables (characteristics).
To understand how system do it technically, you can go through below link.
Master Data Setup - SAP Library
Also you might also need to check technical aspects of BW objects (Cube, Info Objects etc.).
Rgds
Sourabh