The debate hinges on whether Rahu (the north lunar node) is assigned a karakaship or not. The 7-karaka system (Atmakaraka through Darakaraka) excludes Rahu and repeats Mercury for both Gnatikaraka and any remaining slot. The 8-karaka system inserts Pitrukaraka (father significator, Rahu) between Putrakaraka and Gnatikaraka.
K.N. Rao argued for the 7-karaka system on the grounds that Rahu is not a graha (planet) in the classical sense; it is a node and an agent of planetary influence. Other schools counter that the Sutras implicitly account for Rahu's role and that omitting it loses father-related significations.
Key implications: 8-karaka systems will flag paternal issues where 7-karaka systems may misread them. This lesson uses the 7-karaka calculator and notes where 8-karaka readings diverge.
The engine binding computes both; you will learn to interpret the DK (Darakaraka—spouse significator) and PK (Putrakaraka—children significator) placements, which are consistent in both schools.