It remains to be seen what, if anything, will come of Secretary of State Cyrus Vance's peace missions to the Middle East, but it has certainly centered attention on United Nations Security Council Resolution 242, which for 10 years has been the principal basis of international efforts to transquilize the region.

Although 242 has perhaps become the most publicized of all U.N. Security Council declarations, it is by no means fully understood. Even some of the drafters have interpreted it differently from time to time. And now there is talk of amending it to accommodate the Palestine Liberation Organization (PLO).

The most famous and controversial provision of 242 is the section that requires the withdrawal of Israeli-armed forces from territories occupied in the recent conflict, meaning the Six Day War of 1967, which Israel won so quickly and decisively, and which left it in possession of Egypt's Gaza Strip, Jordan's former West Bank, and a slice of the Golan Heights, formerly held by Syria.

What makes 242 historic, however, is that, in effect, it reverses the age-old tradition that to the victor belong the spoils. Until the unanimous passage of 242 on Nov. 22, 1967, it had bee taken for granted that in warfare the winners generally dictate the terms of peace and the post-war disposition of territory.

That's the way it was after World War I, World War II and countless lesser wars over the centuries. But with 242, the United Nations decreed that Israel, as the picture of future peace, would have to surrender the territory it had gained in the 1967 war, even though it acted in self-defense.

If this new doctrine is so desirable, why not make it universal instead of confining it to Israel? In short, why not formalize it through a Security Council Amendment (call it 242-A) that would make it applicable to all members of the United Nations?

That would give the United States the privilege of returning Texas to Mexico; it would require the Soviet Union, at the minimum, to relinquish Latvia, Lithuania, Esthonia and a large part of Poland; China would release Tibet; North Vietnam would free South Vietnam; the victorious World War allies would give East Germany back to West Germany, and, naturally, Manchuria and Korea back to Japan. Finally, the Middle East could be returned to Turkey and the Ottoman Empire. It may be objected that 242-A would be retroactive, but so is 242 itself, since it goes back 10 years.

The United Nations might also pass a second amendment (say, 242-B) to deal with the situation that could arise in the event there is still another Arab-Israel war. It is conceivable that sooner or later the Arabs might win and occupy all of Israel, which, after all, is not very big.

It would be instructive to see how many Arab nations would vote for 242-B if, after defeating and overrunning Israel, it required them to relinquish all their territorial gains and put Israel back in the saddle.

The Arabs profess to be dedicated above all to the creation of a new Palestinian state, supposedly to be carved out of the Gaza Strip and the West Bank occupied by Israel since the 1967 war. "The Palestinian problem is the gut issue," says Hafez Assad, the president of Syria.

Nevertheless, nearly all political factions in Israel feel that the Arab alliance is primarily motivated by Palestine considerations. If Egypt, Syria, Jordan, et al, were so passionately devoted to a new Palestinian state, why didn't they created one when, until 1967, they had full control over the disputed territory now occupied by Israel?

For many years there was little to prevent the Arab states from establishing a Palestinian entity if they had really wanted to. The fact is, to put it bluntly, most of the Arab nations have little use for the divided PLO, except as a thorn in the side of Israel.

Jordan, Lebanon and even Syria, have suffered from the PLO's disruptive tactics; its leadership is so bitterly at cross purposes that it is questionable whether it can speak for the Palestinians as a whole. The PLO has mastered terrorism, but is it capable of responsible government should an independent Palestine finally emerge? There are conflicting reports from the Middle East hinting that the PLO is now willing to accept a provision in Resolution 242 that affirms Israel's right "to live in peace within secure and recognized boundaries free from threats or acts or force," if the declaration is amended to elevate the status of Palestinians.

This seems to have impressed President Carter but not Menachem Begin, the steelish new prime minister of Israel, who, not without reason, doubts the good faith of the PLO in respect to its intention toward his country.

"Should we negotiate with them our self-destruction?" asks Begin, and adds: "We are astonished that free men, men with justice in their hearts, ask us to negotiate with them. They practice genocide, and should be put out of the pale of civilization . . . To ask us to sit down with them, that is asking too much."