In Parashara, a planet's sign and house are the primary tools. A planet in Libra (sign) in the 7th house (domain) is read as oriented toward relationships. The exact degree (7°15' vs 7°45') matters only for strength (combustion, aspect orbs).
In Nadi, every degree within a sign is a distinct zone, carrying its own signification. The Aries sign (0-30°) might be divided as: 0-5° = self, 5-10° = wealth, 10-15° = siblings, 15-20° = spouse/desires, 20-25° = children, 25-30° = enemies/health. A planet at 2° Aries speaks to the self; a planet at 18° Aries speaks to spouse.
This is different from Jaimini's nakshatra-based approach (nakshatras are star groups, unequal in size). It is also different from KP's sub-lord method (which divides nakshatras into 9 unequal parts). Nadi divides signs into 6 or 9 equal degree zones, depending on the text, and each zone has preset meanings.
Application: If Sun is at 7°15' Virgo, the Nadi reader looks up "Sun in 5-10° Virgo" and reads that section's interpretation (which might say "Wealth through intellectual work, peak at age 35"). The interpretation is preset in the nadi text; it is not derived from the chart's overall structure.
Strength of the method: Simplicity, specificity, and psychological richness. The interpretations in nadi texts are often poetic and detailed, resonating with clients.
Weakness: Lack of logical derivation. Why is Sun at 7° Virgo associated with "wealth through intellect, peak at 35"? The nadi text does not explain; it is presented as revealed knowledge. This makes the system hard to debug or improve.
The engine reads planetary degrees and maps them to nadi zones. You will examine your natal planets' degrees and see what the nadi system predicts for them, then cross-check against your actual life events.
The core operation. Take each planet's degree within its sign and read that number as significant in itself. A planet at 3 degrees carries a different meaning from the same planet at 27 degrees of the same sign, independently of house or aspect.
Where the meanings come from. Degree meanings are supplied by tables that vary between sources. This is the method's weakest joint: two practitioners using different tables can derive opposite readings from the same chart and both claim traditional authority. Before using any table, find out where it came from.
The birth-time dependency. Degrees change continuously, and the Moon moves roughly half a degree an hour. A birth time uncertain by an hour makes the Moon's degree uncertain by half a degree, which may cross a meaning boundary. Slower planets are more forgiving, but the ascendant is worse: it moves about a degree every four minutes.
Disciplined practice. Fix one table before you read, record which table you used, and do not switch tables after seeing the outcome. Switching sources retrospectively is how a method that cannot be tested starts to look as though it works.