In Iran, the stamp of Islam is everywhere. The ranking of Iran's ruling clergy

The Islamic Republic of Iran is the world's first and only Shiite theocracy -- ruled by clerics of the Shia sect of Islam, generally known as ``mullahs'' in the West. In fact, Iranians rarely refer to the 180,000 religious men in Iran as mullahs, except when talking to Westerners. Collectively, they are called the ulema, meaning learned men or Islamic scholars.

The Shiite ulema is divided into a structured hierarchy. It is impossible to discern a cleric's rank by his appearance, however, because all wear similar robes. The distinguishing factor is that sayyids, those considered descendants of the Prophet Muhammad (of which Ayatollah Khomeini is one), wear black turbans; other clerics wear white ones.

If a cleric attends theological school and attains a reputation as a jurisprudent, he can become acknowledged as a mujtahid -- one qualified to use independent judgment or original thinking in interpreting the Koran.

The title of ayatollah (meaning ``sign of God'') is bestowed on a theologian who attains a scholarly reputation. From the ranks of ayatollahs emerge several marja-i taqlids, (meaning ``the source of imitation''), who could be called the ``grand'' ayatollahs. At present there are about six, one of whom is Ayatollah Khomeini.

It is the duty of all lay Shiites to choose a living mujtahid as a spiritual guide and follow his teachings. Preferably, this guide should be the single most knowledgeable juris-prudent of the era. Without such emulation, a Shiite's religious practice is considered invalid. Each prominent ayatollah typically has his own entourage of supporters whose loyalty changes only when he dies. Thus, technically Khomeini is not the leader of all Iranian Shiites. ``Don't tell anybody,'' confided o ne Iranian, ``but much as I revere Imam Khomeini, actually I follow his teacher Ayatollah Khoi, who lives in Najaf, Iraq.''

Nonetheless, Khomeini's mystique as the leader of Iran's revolution and founder of the Islamic Republic has earned him the honorary title of imam, meaning spiritual leader of the community.

The name harks back to the original 12 imams revered by the Shiites and whose infallibility is ascribed to Khomeini by his supporters. It indicates almost supernatural power.

Khomeini's role as leader was institutionalized in the Constitution, which gave him the title velayat-e faqih (supreme theological guide.) This implies guardianship of the Muslim community, but Khomeini has interpreted it to mean political rule by a single jurisprudent.

Khomeini reportedly has not discouraged his followers from claiming that he is the current representative on earth of the Imam Mahdi (the Shiites' twelfth imam) and is in communication with him to carry out his wishes. Khomeini has said that his government is merely standing in for the Imam Mahdi, to whom he would hand over power when he comes.

Many Iranians regularly include in their prayers, ``God, God, send the Mahdi soon and keep Khomeini alive until his return.''

Until that time, Shiite theology maintains that all governments are illegitimate. However, the Iranian government claims that the Islamic Republic is the world's only legitimate state, since it is the first to implement true Islamic law.

Ayatollah Hussein Ali Montazeri, Khomeini's prot'eg'e, is presumed to inherit the title when Khomeini dies. In preparation for this, Ayatollah Montazeri recently wrote his risala, the requisite manual of religious practice for his followers, and was elevated to the level of marja-i taqlid.