Grammatical Analysis
Saddhammapajjotikā: [f.] The Illuminator of the True Dhamma. Formed by saddhamma (true doctrine) + pajjotikā (illuminating, lighting up).
Orthodox Definition
The Saddhammapajjotikā is the commentary on the Niddesa (both the Mahāniddesa and Cūḷaniddesa). It was authored by Venerable Upasena, a monk who resided at the Mahāvihāra in Sri Lanka.
Because the Niddesa itself is already a canonical commentary (attributed to Sāriputta) on the archaic Suttanipāta, Upasena’s work functions essentially as a sub-commentary to Sāriputta’s exegesis. Upasena clarifies the ancient etymologies and Abhidhammic lists that Sāriputta used, ensuring that the precise Mahāvihāra interpretations of these extremely difficult texts were not lost.