In his piece on the ABM Treaty {op-ed, Sept. 29}, Sen. Ernest Hollings restates the essence of the administration's "reinterpretation" as though it were a middle course. He bases his position on the negotiating record, to which he says we must give precedence in interpretation, but his own position on the issue is regrettably based on a fatally flawed misunderstanding of that record.

Sen. Hollings states, for example, that "Article II of the treaty clearly controls those ABM systems current at the time of the signing of the treaty," while "Agreed Statement D clearly controls those ABM systems based on 'other physical principles' in the future." His dichotomy is clear, but it is not sustained by the negotiating record. Sen. Hollings quotes me as having said in 1971 that the "question of constraints on future systems would be settled elsewhere than in Article II." But in saying that constraints would be settled elsewhere, I was not saying that the definitional Article II did not apply to future systems. In fact, I said precisely the opposite. In proposing on behalf of the United States the language subsequently accepted in the treaty, on Dec. 20, 1971, I stated to my Soviet counterpart negotiator that "the Soviet side, as well as the American, recognized that there could be future systems, and while the question of constraints on future systems would be settled elsewhere than in Article II, the correct way of indicating a valid connection between components and systems in Article II would be to include the word 'currently.' " Inclusion of the words "currently consisting of" in listing ABM components based on current technology made crystal clear that the identified components were not a complete and exclusive listing.

As Ambassador Paul Nitze stated in a speech on May 30, 1985, "That future types of permitted ABM systems and components were contemplated is obvious from the language of Article II, which defines ABM systems as 'currently consisting of' ABM interceptor missiles, launchers, and radars."

The second major point Sen. Hollings raises is that, in his reading, "Agreed Statement D clearly controls those ABM systems based on 'other physical principles' in the future." Because that statement deals only with deployment, he contends that only deployment of future systems is limited. The statement does deal only with deployment, but contrary to the senator's interpretation and that of other would-be reinterpreters, the U.S. delegation never sought to have that provision deal with anything other than deployment. The constraint banning development and testing of space-based and other mobile ABM components is contained in Article V(1): "Each Party undertakes not to develop, test, or deploy ABM systems or components which are sea-based, air-based, space-based, or mobile land-based." And Article II makes clear that the treaty covers future as well as then-current components. So does the negotiating record. When Article V(1) was being agreed to, on Sept. 15, 1971, the Soviet negotiator, Victor Karpov, confirmed this understanding with his American counterpart. The record reads: "Karpov agreed with Graybeal's interpretation that the Soviet text meant 'any type of present or future components' of ABM systems." RAYMOND L. GARTHOFF The Brookings Institution Washington The writer was on the government team that negotiated the ABM Treaty.

Sen. Hollings is right. The Nunn-Levin amendment corrupts the Constitution and undermines the authority of the Senate in the treaty ratification process by inviting the House to play an equal role with respect to the ABM Treaty.

Sens. Sam Nunn and Carl Levin have established a requirement for passage of a Joint Resolution -- requiring House and Senate approval -- before a president could develop or test mobile/space-based defenses against nuclear ballistic missile attack. Unlike SALT I, which was agreed to by both houses of Congress in Public Law 92-448, the Senate alone advised and consented to the ratification of the ABM Treaty. Now, in a misguided effort to derail the potential implementation of a broad interpretation of the accord, the Senate seems determined to convey upon the houses of Congress treaty-associated prerogatives not supported by the Constitution.

The political motivations behind this effort are quite clear; the constitutional logic is certainly not. JOSEPH T. MAYER Arlington