This letter writes the velar nasal pronounced with the lips brought together, the rounding running through the whole sound. The velar region therefore carries the same three way division, plain, palatalised and rounded, in its nasal as in its fricative. The nasal letters form a block of eight, running from the velar nasal at the back of the mouth to the bilabial at the lips, with the palatal and the positionally restricted signs among them. Eight signs for the nasals is an unusual provision, and it exists because the recitation distinguished all eight. It stands thirty-seventh in the alphabet as a whole and twenty-first of the thirty-eight consonants, between Avestan Ngye and Avestan Ne.
The order is the work of the people who devised the alphabet rather than an inheritance from anywhere, and reading the list straight through recovers the analysis they were working from. The Avestan alphabet was made for one text. That is unusual, and it explains a repertoire far larger than the languages around it needed. A script serving letters, accounts and contracts can afford to let two sounds share a shape, because context recovers the sense. A script serving a recitation cannot, because there the sound is the thing being preserved. Transliteration is where the size of the letter list becomes visible to a reader who does not know the script. A scholarly edition carries accents, dots, rings and length marks, and every one of those marks stands in for a separate Avestan letter that the Roman alphabet has no room for.