Varga
Navamsha (D9)
The D9 or navamsha divides each sign in nine
The D9 or navamsha divides each sign in nine. It is the most important divisional chart — the chart of marriage and of a planet's inner strength, read almost as a second birth chart.
Each sign yields nine parts of 3°20′ — one per nakshatra pada — counted from the movable, fixed or dual sign's starting point. Parashara weighs the navamsha above every varga but the rashi; a graha in the same sign in both (vargottama) approaches own-sign strength.
— Brihat Parashara Hora Shastra ṣoḍaśavarga adhyāya
Division: 9 × 3°20′, aligned to the padas. Used for spouse and marriage (with the 7th and Venus), for the maturity a planet grows into, and for dignity verification — a debilitated D1 graha exalted in D9 is read very differently. The engine's dignity_in_varga conditions and vargottama facts run on it.