The script used by such inscriptions is commonly known as the Tamil-Brahmi or "Tamili script" and differs in many ways from standard Ashokan Brahmi. The earliest inscriptions which are accepted examples of Tamil writing date to the Ashokan period. The Tamil script, like the other Brahmic scripts, is thought to have evolved from the original Brahmi script. The Tamil script is written from left to right. In every case, the vowel marker is different from the standalone character for the vowel. Others are written by adding a vowel-specific suffix to the consonant, yet others a prefix and still other vowels require adding both a prefix and a suffix to the consonant. Some vowels require the basic shape of the consonant to be altered in a way that is specific to that vowel. The combinant letters are formed by adding a vowel marker to the consonant. The complete script, therefore, consists of the 31 letters in their independent form and an additional 216 combinant letters, for a total of 247 (12+18+216+1) combinations ( உயிர்மெய்யெழுத்து, uyirmeyyeḻuttu, "soul-body-letters") of a consonant and a vowel, a mute consonant or a vowel alone. However, it is listed at the end of the vowel set.
ஃ is called "அக்கு", akku and is classified in Tamil orthography as being neither a consonant nor a vowel. Diverging evolution of Tamil-Brahmi script (center column) into the Vatteluttu alphabet (leftmost column) and the Tamil script (rightmost column)