If we do a search in the BuddhaNexus, we would find a couple of occurrences of the grammatical expression yin byed kyi mtha’ can, that occurs in some śabdaśāstras and pramāṇaśāstras. It is also used by Rong-zom-pa. This must refer to a kind of Sanskrit suffix. It occurs in the context of taddhitapratyaya (de la phan pa’i rkyen) “secondary suffix” and kṛtpratyaya (byed pa’i rkyen) “primary suffix.” Some sources mention yin byed kyi rkyen. We may, for now, take rkyen and mtha’ to be synonymous. This can be deduced from the use of the expressions kṛtpratyaya and kṛdanta. For the want of a better suggestion, I am considering if yin byed kyi mtha’/rkyen is a Tibetan rendering of bhāvapratyaya, which has been translated elsewhere as dngos po’i rkyen. In Rong-zom-pa’s case, the term yin byed kyi mtha’ can should not be understood as the suffix itself but as referring to a word with this suffix. If this holds, the term yin byed kyi mtha’ can may be translated as “a [word] that possesses being-making/causing suffix.” This bhāvapratyaya is said to be an “abstraction/nominalizing suffix” (i.e. tva or tā).