Avestan I and Two Ways of Writing a Vowel

The Indic scripts of the same centuries wrote this vowel as a mark attached to a consonant. Avestan writes it as a letter on the line. Both solutions preserve the sound; only one of them treats the vowel as a thing in its own right. A script made in the Sasanian period for a text composed a thousand years and more earlier is an act of preservation rather than of composition. Nothing was being written down for the first time. What was being done was the fixing, in a form that would not drift, of something priests already held in memory. The script was put to a second use as well.

Pazand is Middle Persian written in Avestan letters, taken up precisely because those letters record vowels and the Pahlavi ones did not, and it is the clearest practical demonstration of what the alphabet was good for. In the digital record the letter is encoded at U+10B0C AVESTAN LETTER I. The whole Avestan block lies above the Basic Multilingual Plane, so each character needs a surrogate pair in the encodings that use them, and a font carrying the script is required before anything appears on a screen at all. Zoroastrianism is a living religion with a small community, and the Avesta is its liturgy rather than its archive. The letters of this alphabet are therefore not an antiquarian matter. They record sounds a priest is still expected to produce.