Hello, I have a question regarding the 4 additional letters of the Perso-Arabic script : پ چ گ ژ. How do they come into being ? How have they been chosen ? Have there been some hesitations, some scribal variations before it settled to those 4 shapes ? I'm asking, because if you analyze the actual Arabic alphabet, you clearly see that there is a pattern between many of the non-dotted and dotted letters (or if already dotted, vs. the triple-dotted letters). Every time, the extra-dotted letter will roughly keep the same place of articulation, the same voicedness, but will become fricative, or, if already fricative, a "modified" fricative. (See table below) The picture got blurred because Arabic underwent some spirantization, namely p > f and g > ǧ, and less importanly for Persian, two emphatics lost their primary values, ض and ظ (ś in my table denotes the lateral fricative, present both as plain and as emphatic). So, I guess, when they wanted to create the new letters, they tried to fill the voicedness gaps let by Arabic by using the extra dots as a voice-inversion operator : p based on b (ب -> پ), g based on k (ك -> گ), č based on ǧ (ج -> چ). Only z / ž (ز -> ژ ) respects the dots' primary function. Here is in red what I propose it should have been : p>f b t d s z s t k g>ǧ ħ 3 ف ب ت د س ز ص ط ك ج ح ع f v θ ð ś>š ž ś>d θ>ð č ǧ x ɣ ڤ پ ث ذ ش ژ ض ظ گ چ خ غ ( "v" in my table is just here for completeness, as I guess that و was originally pronounced "w" in Persian (?) and changed to "v" only later so that wasn't a problem when the Arabic alphabet got adopted. Someone confirm?) Did the spirantization changes that Arabic undergo already take place when the Arabic script made it to Persia ? People at that period were seemingly very aware of phonetics, how come they didn't see that or try to stick to it ? Thank you!