 For the consonants whose shape does not depend on the following vowels, the vowel signs must be used after the consonant symbol.Compared to the Avestan alphabet Old Persian notably lacks voiced fricatives, but includes the sign "ç" (of uncertain pronunciation) and a sign for the non-native "l".Notably, in common with the Brahmic scripts, there appears to be no distinction between a consonant followed by an "a" and a consonant followed by nothing.