It would Be audacious to claim that we have understood every fresh development in Sen. Frank Church's SALT position as it has emerged over the last few weeks, rather in the disjointed and endlessly surprising manner of clowns climbing out of a circus car. His current stand, however, as best we can make it out, calls for President Carter to "affirm" that the Soviet troops in Cuba "are not engaged in a combat role" and "will not become a threat to any country in the Western Hemisphere." The Senate would then proceed, the chairman of the Senate Foreign Relations Committee hopes, to ratify the treaty.

Well, okay. Jimmy Carter engaged in a certain amount of shadow play to get himself out of the box he had put himself in by promising prematurely that he would not tolerate the "status quo," whatever it was -- it has still not been established what it was beyond a resonable doubt. Frank Church had locked himself into a similar box by demanding that the Soviets withdraw their troops before the Senate takes up SALT, and he is entitled to a certain amount of shadow play of his own. The demand for presidential assurance would be attached as an "understanding" to the Senate resolution of ratification of SALT, not to the treaty itself. The significance of this is that the Senate would not be making a direct, and unenforceable, demand on the Soviet Union. But the Senate would be doing something to satisfy those senators who feel that something must be done. The administration has its lawyers looking at the fine print, and figures it can crack the case.

So much for Mr. Church, who is running for reelection in a state said to he highly inflamed against the very idea of SALT. The practical effect of his latest move is to clear the way for the treaty to reach the Senate floor, perhaps by the end of October; a vote on it could come by Thanksgiving. This is right.

The evident sense of the Senate is to move past the troops issue, which is generally and correctly perceived to be a poorly designed rampart on which to take a stand either on Soviet global policy as a whole or on Jimmy Carter's conduct of his office. Those who believe that the treaty contributes to American security and that its defeat would impair American security are anxious to call the question before things get worse. Those who oppose the treaty flat out believe things are bad enough. A third group, the swing group, has used the ratification process to apply leverage and to generate steam for higher defense spending and for a tougher foreign policy. Most members of this group appear to believe they have made their point. In brief, the end is in sight.