 An unwritten rule of addressing for Shia clerics has been developed after the 1980s as a result of Iranian Revolution, despite the fact no official institutional way of conferring titles is available.Since 1979, the number of individuals who call themselves an Ayatollah, instead of being recipient of that title, has raised dramatically.The title that was previously customary for addressing a "Marja'", was gradually applied to an established "Mujtahid".