THE WORD "all" was accidentally dropped from an editorial in yesterday's paper, creating a technical error, though leaving the point intact. The editorial dealt with changes the Reagan administration is considering in current law and policy dealing with nuclear non-proliferation. The issue involved is an important one, which we would like to set straight.

The inaccuracy occurred in describing the administration's proposed elimination of what many people consider the single most important feature of the Nuclear Non-Proliferation Act of 1978, the governing law in this field. It is the provision that no nuclear export be made unless the recipient country has accepted full-scope safeguards--that is, international safeguards on all its nuclear facilities, whether imported or indigenous.

The law applies this requirement to all U.S. customers including those whose pre-existing nuclear agreements with the United States do not include this condition. What the administration is now proposing is to remove the requirement from this group of nations. Hence it terms the proposed change "the elimination of retroactivity." Among the countries that would be affected are India, South Africa, Brazil and Argentina--all high on anyone's list of potential (or actual) proliferators.

Although the proposal does not extend to dropping the full-scope safeguards requirement for agreements to be negotiated in the future, it would amount to the same thing. As the law now stands, the full-scope safeguards requirement is its centerpiece. It gives credibility to the earlier U.S. policy that aimed at persuading all nuclear suppliers to adopt this standard. Congress was aware that adding a new requirement for countries that had been nuclear customers for years would cause difficulties. (It was, for example, at the center of the battle royal between the Carter administration and Congress last fall over a proposed export to India.) But Congress believed that this particular requirement was important enough to a successful non-proliferation effort to warrant taking the step.

Our point therefore remains that dropping the full-scope safeguards requirement for some countries (elimination of retroactivity) or for all would have in practice the same result. And that result would likely accelerate the spread of nuclear weapons technology.