in Iran, given its use in a fragmentary manuscript of the Psalms of David. The script of the psalms has altogether 18 graphemes, 5 more than Book Pahlavi and one less than Inscriptional Pahlavi. As in Book Pahlavi, letters are connected to each other. The only other surviving source of Psalter Pahlavi are the inscriptions on a bronze processional cross found at Herat, in present-day Afghanistan. Due to the dearth of comparable material, some words and phrases in both sources remain undeciphered. Of the 18 characters, 9 connect in all four traditional abjad positions, while 9 connect only on their right or are isolated. Numbers are built from units of 1, 2, 3, 4, 10, 20, and 100. The numbers 10 and 20 join on both sides, but the numbers 1, 2, 3, and 4 only join on the right, and if they are followed by an additional digit, they lose their tail, which is visually evident in their isolated forms. There are 12 encoded punctuation characters, and many are similar to those found in Syriac. The section marks are written in half-red and half-black, and several documents have entire sections in both black and red, as a means of distinction. Book Pahlavi Book Pahlavi is a smoother script in which letters are joined to each other and often form complicated ligatures. Book Pahlavi was the most common form of the script, with only 13 graphemes representing 24 sounds. The formal coalescence of originally different letters caused ambiguity, and the letters became even less distinct when they formed part of a ligature. In its later forms, attempts were made to improve the consonantary and reduce ambiguity through diacritic marks. Book Pahlavi continued to be in common use until about AD 900. After that date, Pahlavi was preserved only by the Zoroastrian clergy. Logograms In both Inscriptional and Book Pahlavi, many common words, including even pronouns, particles, numerals, and auxiliaries, were spelled according to their Aramaic equivalents, which were used as logograms. For example, the word for "dog" was written as (Aramaic kalbā) but pronounced sag; and the word for "bread" would be written as Aramaic (laḥmā) but understood as the sign for Iranian nān. These words were known as huzvārishn. Such a logogram could also be followed by letters expressing parts of the Persian word phonetically, e.g. for pitar "father". The grammatical endings were usually written phonetically. A logogram did