CUSTODY OF the American hostages in Iran is about to be shifted from the terrorists who have held them for four months to the Revolutionary Council, which accepts at least a modicum of obligation to act according to international norms.This could mean an easing of the harsh conditions under which the 50 hostages have been held. It could also mean an early visit by the United Nations Commission now in Tehran, permitting the first independent audit of the numbers and health of the prisoners. Finally, it could mean that, for a change, Washington will be negotiating for the hostages' release with a body that can be held publicly accountable. The people who have been holding the Americans -- in defiance of those Iranians who wish to impose the discipline of government on the disorder of revolution -- would be out of the picture.

To be sure, there's a long way to go. Even if the captors hand over the hostages, the hostages' future and disposition will be a matter of contention between President Bani-Sadr, who heads the Revolutionary Council, and his political rivals on the council. The latter are thought to be well placed to prevail in coming elections to the parliament; and it is the parliament to whom Ayatollah Khomeini, still the final arbiter, has given the job of determining the hostages' fate. It was on Mr. Bani-Sadr's assurance that the hostage issue would be promptly resolved that the United Nations dispatched the commission of inquiry that has just finished listening to Iranians' grievances against the former shah and his American connection. But whether Mr. Bani-Sadr is prepared to deliver on his pledge has not yet been established.Until then, Americans cannot avoid asking whether they are being teased.

Part of the answer will be determined by the success of this attempt to take charge of the government in Tehran in fact as well as in name. A no less important part will be determined by the particular form of Iran's demands on the United States. Not too many Americans can believe that the therapeutic value of confessing past error in Iran would compensate for the indignity of it or for the distortion of history that a full-scale confession would involve or for the encouragement it would offer to other would-be hostage-takers. Our sense of it is that most Americans feel President Carter may have already paid too much; the pocket from which a further final payment would come is empty. We agree.The seizing of the embassy was an utterly unjustifiable act. The United States is reacting to Iran now out of contrition but under duress. If Iran is serious abour normalizing relations with Washington after the crisis, it will bring the crisis quickly to a close.