President Reagan has pushed to center stage the great unfinished business of the Camp David accords by focusing on the future of the West Bank and Gaza Strip in his television address last night.

The West Bank, or Judea and Samaria as the Israelis refer to the territory, and the Gaza Strip figured only as an annex to the agreements signed by Anwar Sadat, Menachem Begin and Jimmy Carter on March 26, 1979. But that annex contained the hard nut of the Palestinian issue that the negotiations at Camp David could not crack.

The Camp David accords do not specifically mention the question of Jewish settlements on the West Bank but call for a Jordanian role in negotiations about the region's future. Although there is no language in the text to suggest any Jordanian role in their future, neither is there language that would forbid it. That question is left to the negotiators.

While not mentioned in the accords directly, the settlements issue figured prominently in the closing stages of the talks and provided the source of a major misunderstanding between Carter and Begin on the one hand and Carter and Sadat on the other, according to sources familiar with the negotiations.

Such misunderstandings and ambiguities in the legacy of the Camp David talks have provided ample opportunity for all parties to have radically different versions of what the accords intended and what the territories' future should be.

The future of the West Bank and Gaza Strip was covered in an annex to the main Camp David document, which dealt primarily with return of the Sinai and establishment of relations between Israel and Egypt.

In the annex, referred to as "Framework for Peace in the Middle East," the Camp David negotiators agreed to an outline for future negotiations that in effect finessed widespread differences that emerged between Begin and Sadat at the Camp David conference table. Rather than allow these issues to delay the peace agreement between Israel and Egypt, they were pushed aside temporarily.

In broad outline, the agreement called for:

* Negotiations for election of a "self-governing authority" for the West Bank and Gaza and establishment of the powers and responsibilities of this authority. Once established, it would be in effect for a "transitional period" of five years.

* No later than three years into the period, negotiations were to begin on the "final status" of the West Bank and Gaza and on a peace treaty between Israel and Jordan.

* The negotiated arrangements for the "final status" were to be submitted to inhabitants for a vote.

* An objective of all these discussions was to be "the resolution of the Palestinian problem in all its aspects."

The accords called for Jordanian participation in these negotiations and allowed for Palestinians to sit with the Egyptian and Jordanian delegations. Neither Jordan nor any Palestinians has agreed to participate in the discussions.

Left begging was the substantive questions of what type of future was envisioned for the West Bank and Gaza. From the outset, Israel clearly had a highly restricted interpretation of this future while Egypt thought the negotiations should provide the vehicle for complete self-determination of the West Bank's inhabitants.

Beginning from these widely separated positions, the autonomy talks that began in June, 1979, have been an exercise in frustration, never bridging the first basic issue: setting up a framework for electing the self-governing authority and establishing its powers.

For U.S. and Egyptian officials, the Israeli settlements policy has provided one of the major irritants of the last three years. The issue was joined even before the Camp David documents were signed, according to more than one knowledgeable source.

The subject apparently arose on the next-to-last day of the Camp David deliberations when Carter sought to persuade Begin to agree to a freeze on settlements during negotiations toward a final arrangement for the West Bank and Gaza, in other words, for the full five years of the transitional period. A line in the draft of the treaty covered the issue.

Begin is said to have resisted such a pledge, until he finally agreed after extensive discussions to give Carter an answer by letter, a device used for several issues left unresolved at the close of Camp David talks. The line was stricken from the draft.

Carter is said to be convinced that he understood that Begin had given the pledge during their discussions and that Begin's promised letter was to encompass this. Carter subsequently told Sadat that he had such a pledge, which was highly reassuring to the Egyptian leader.

Begin's letter on the settlements moratorium was not delivered, along with others covering issues not mentioned in the accords. Sadat, who signed the accords under the impression given by Carter that the latter had received a five-year moratorium pledge from Begin, learned of the apparent misunderstanding just before returning to Cairo and is said to have told a high-ranking U.S. official, "This is a bad sign."

When the promised letter finally arrived, either within days or weeks, according to different versions, it promised a freeze not for the five-year transitional period but for three months while details of the Egyptian-Israeli portion of the accords were finalized.

Carter is said to have been surprised and angered by the letter, ordering it returned as unacceptable. Israelis insist that Carter had misunderstood what Begin had said during the Camp David discussions.

The issue apparently proved crucial in subsequent U.S. efforts to gain the cooperation of Jordan and other Middle East nations in the Camp David process.

Harold B. Saunders, former assistant secretary of state for Near East and South Asian affairs, said yesterday that, immediately following the Camp David agreement, "failure to make the moratorium stick" proved to be one of the most important factors in failing to gain the trust and cooperation of Jordan's King Hussein and other Arab leaders.

They looked upon the issue of control over land in the West Bank as a measuring rod of U.S. influence with the Israeli government, he said.