Expanded process of dialogue is key legacy of summit. SUMMIT AFTERGLOW

The new buzzword is ``process.'' As Washington winds down from the intense pressures of last week's superpower summit, this phrase keeps cropping up in assessments of issues ranging from human rights to Afghanistan to ``star wars.'' The analysis by participants and Washington observers echoes the joint summit statement, which called for ``a process intended to improve strategic stability and reduce the risk of conflict.''

Expectation of an evolving civil dialogue is a realistic reading of a summit that neither settled for mere public relations like the first meeting between President Reagan and Soviet leader Mikhail Gorbachev in 1985, nor ended in recriminations like their get-together last year, nor produced any major breakthroughs of its own. The success of this summit will be judged not by the mood left over this week, but by what has happened in another year or two or three.

The deliberate launching of a long-term process of mutual adjustment is most striking in the key issue of Mr. Reagan's Strategic Defense Initiative (SDI or ``star wars''). The Soviets charge SDI would violate the 1972 Anti-Ballistic-Missile (ABM) Treaty if its program of testing were unrestricted.

Thus, in a last-minute compromise the two sides ``agreed to disagree,'' as several American officials and observers phrase it - but they did instruct their negotiators in Geneva to ``work out an agreement'' on continued compliance with the treaty banning tests of ABM (SDI) systems or full components in space. This looks like starting a rolling process of consultation over the seven or 10 years of continued compliance with the treaty

Addressing the issue in an especially convoluted sentence in their concluding statement, the two men declared: ``Taking into account the preparation of the treaty on strategic offensive arms, the leaders of the two countries also instructed their delegations in Geneva to work out an agreement that would commit the sides to observe the ABM Treaty as signed in 1972, while conducting their research, development, and testing as required, which are permitted by the ABM Treaty, and not to withdraw from the ABM Treaty, for a specified period of time.''

For the first time this confers presidential authority on working-level US officials in Geneva to negotiate with the Soviets about what the two sides understand by the continued observance of the ABM Treaty. This authorization perpetuates the method adopted at the Washington summit of having the President and general secretary concentrate on broad statements and their personal relationship, while devolving the real bargaining to the foreign ministers and their top assistants.

The authorization also ends the almost year-old impasse in which the State Department, Defense Department, and National Security Council were at such loggerheads and so preoccupied by the Iran-contra affair that Washington's ``inter-agency'' policy-making process in space defense did not function. The Geneva negotiators were consequently left without instructions, according to a US official.

The guidelines for the negotiators remain murky. The Americans say the phrase ``testing as required'' gives them license to follow the administration's preferred ``broad'' interpretation of the treaty and conduct realistic tests of SDI systems or full components in space.

The Soviets, by contrast, even though they failed to get a pledge to abide by the ABM Treaty ``as signed and ratified,'' reserve the right to contest Reagan's permissive interpretation of ABM restrictions at a later date. For the time being they are relying on Congress's legal restriction of American SDI testing to the ``narrow'' interpretation.

The key issue of whether either side has a veto over eventual ABM deployments of the other also remains murky. Here the compromise language in the final statement says that ``Intensive discussions of strategic stability shall begin not later than three years before the end of the specified period [of treaty compliance], after which, in the event the sides have not agreed otherwise, each side will be free to decide its course of action.''

The US thus did not win explicit approval of SDI deployment after the period of continued compliance with the ABM Treaty. Nor did the Soviet Union win limits on deployment. But the Soviets did write into the summit statement a linkage between defense and offense in ``taking into account'' the ongoing Strategic Arms Reduction Talks (START). And it did reserve the unilateral right (``each side will be free to decide its course of action'') to abandon any agreed START cuts the moment the US deploys SDI, in order to overwhelm the American defense with an increase in Soviet offensive warheads.

An ongoing process is also programmed for the START negotiations to cut long-range arsenals in half, preferably with agreement in time for signing of a treaty at the Moscow summit to be held in the first half of 1988. The Washington summit advanced this agreement by setting a sublimit of 4900 ballistic missile warheads (under the already agreed overall warhead ceiling of 6000) and establishing the principle that warheads on long-range nuclear sea-launched cruise missiles (SLCMs) will be limited. Previously the US had refused to curb SLCMs; it now accepts limits, so long as adequate verification is set up to distinguish between conventional and nuclear SLCMs, and so long as the SLCM numbers are in addition to rather than deducted from the overall 6000 strategic warheads.

Soviet concessions in START last week included acceptance of a ban on encryption of telemetry in missile tests and an unusual promise to make ``open diplays'' for satellite inspection of ``submarine ports'' as well as missile and bomber bases.

The Soviets also agreed to put into writing in some form their previous promise to cut in half their ballistic missile ``throw weight'' [launch capability] and not to increase it subsequently.