These graffiti usually appear singly, though on occasion may be found in groups of two or three, and are thought to have been family, clan, or religious symbols.[35] In 1935, C.L. Fábri proposed that symbols found on Mauryan punch-marked coins were remnants of the Indus script that had survived the collapse of the Indus civilization.[36] Iravatham Mahadevan, decipherer of Tamil-Brahmi and a noted expert on the Indus script, has supported the idea that both those semiotic traditions may have some continuity with the Indus script, but regarding the idea of continuity with Brahmi, he has categorically stated that he does not believe that theory "at all".[34]