The Sign Above the Line

Brahmi writes this vowel in two entirely different ways depending on where it stands. At the head of a word it has an independent letter of its own; anywhere else it is a mark attached to the consonant it follows, replacing that consonant's inherent a. The two forms are not variants of one shape and a learner has to acquire both, which is true of every vowel in the script and is one of the things that makes an abugida harder to teach than it looks. The mark sits above the line of writing, in the band the script reserves for the front vowels, and the descendants of Brahmi keep it there.

Where the descendants diverge is in how far the mark travels. In several of the northern scripts the corresponding sign eventually detached itself and came to be written before the consonant it is pronounced after, so a reader has to hold the mark in mind until the consonant arrives. Brahmi itself does not do this, and the change is one of the clearer markers of the distance between the parent script and its later children. The Prakrit of the third century BCE gave scribes no shortage of occasions to write it, so the mark is well attested from the earliest surviving material onwards, which is not true of every sign in the vowel series.