Thank you very much, Embodied and y not!
From your clues, I found out from one of Lal’s posts that Indriya here refers to the panca indriya, or the dominant characteristics and capabilities (gathi) of beings. There are five: sati, samadhi, panna, saddha and viriya. As there are different languages used in this forum (Sinhalese, Pali, etc.), shaddha should correspond to saddha, and pragna should correspond to prajna or panna, I think.
However, is there anyone who can elaborate on why viriya types contemplate better on anicca, saddha types on dukkha, and panna types on anatta? This is important to me as I am wondering how best to contemplate on anicca, dukkha and anatta.
Thank you very much in advance for any kind help or advice you can provide.