The United States has guaranteed, "on the basis of assurances received from the government of Israel," the safety of Palestinian guerrillas departing Beirut as well as that of their families and other noncombatant Palestinians left behind, according to a State Department fact sheet distributed yesterday.

In addition to setting down in public for the first time the timetable and the terms of the evacuation, the fact sheet provides an additional glimpse of some of the points that have been the subject of intense negotiations among the United States, the governments of Lebanon and Israel and the Palestine Liberation Organization over the past two months.

Besides serving as the guarantor of Israeli behavior during the evacuation, the United States also will guarantee the conduct of "certain Lebanese groups with which it has been in touch," presumably the Lebanese forces of Christian leader Bashir Gemayel. The Lebanese government, meanwhile, has guaranteed Palestinian safety "on the basis of having secured assurances from armed groups with which it has been in touch."

Between seven and eight Lebanese Army battalions, or 2,500 to 3,500 men, will be assigned to the operation. That contingent is to coordinate its activities with those of the U.S.-French-Italian force through a committee whose deliberations "will be conducted in such a way as to minimize misunderstandings and to forestall difficulties."

Recalling the anxiety and distrust on all sides that have characterized the negotiations, the document repeatedly emphasizes that any changes in the evacuation schedule will be "continually monitored," approved and communicated to all parties.

Regarding the multinational force, the fact sheet states that while "there is no intention or expectation that U.S. forces will become involved in hostilities in Beirut . . . we cannot rule out isolated acts of violence." It adds that "all appropriate precautions will be taken to assure the safety of U.S. military personnel during their brief assignment to Lebanon." The multinational force "will depart Lebanon not later than 30 days after arrival."

The timetable for the PLO departure allows for some flexibility but also contains a warning: "In the event that the departure . . . does not take place in accord with the agreed and predetermined schedule, the mandate of the MNF [multinational force] will terminate immediately and all MNF personnel will leave Lebanon forthwith."

Although the Marine role in Lebanon is "peace-keeping," the Marines will be armed and the documents acknowledge that fighting may occur.

"In carrying out its mission, the American force will not engage in combat," states the official note from Lebanese Deputy Prime Minister Fuad Boutros requesting U.S. involvement in the multinational force. "It may, however, exercise the right of self-defense."

The agreement calls for all departures to take place "in daylight hours," and stipulates that overland convoys "should cross the border into Syria with no stops en route." When a convoy passes through Israeli military positions, the agreement calls for the Israelis to "clear the route for the temporary period in which the convoy is running."

The departing Palestinians each are allowed to carry out one hand weapon and ammunition. All remaining weaponry, munitions and military equipment are to be turned over to the Lebanese Army "as gifts." Syrian forces will be allowed to carry out their weapons and equipment.

The plan stipulates that the PLO's military and political leadership will accompany departing personnel in "proportionate share . . . throughout all stages of the departure operation." There is no mention of the expected departure date or destination of PLO Chairman Yasser Arafat; unconfirmed reports have said he will go to Tunisia.

Although the fact sheet cautions that the schedule is "subject to revision as may be necessary because of logistical requirements and because of any necessary shift in the setting of Departure Day," the tentative chronology is as follows:

* Aug. 21 -- Approximately 350 French troops land at the port of Beirut at about 5 a.m. Beirut time and deploy in the port area. Lebanese armed forces assist in PLO departure preparations, deploy along the Green Line and take up positions formerly occupied by the PLO. The initial group of PLO guerrillas, possibly including the wounded and ill who are scheduled to go to Greece, will assemble at the port and will leave by sea in the afternoon or possibly on Sunday. It is assumed the group will sail approximately 12 hours to Larnaca, Cyprus, then be transferred, presumably by air, to Jordan or Iraq.

* Aug. 22 -- All groups destined for Jordan or Iraq will have boarded ship and sailed from Beirut. Groups destined for Tunisia will assemble at the port for departure by sea.

* Aug. 23 -- PLO personnel destined for South Yemen will assemble and depart by sea.

* Aug. 24 -- Assembly and departure by sea of PLO personnel destined for North Yemen.

* Aug. 25 -- "Provided that satisfactory logistical arrangements have been completed," initial PLO groups destined for Syria will leave over the Beirut-Damascus highway. Troops from the original French contingent, and the Lebanese Army, will have taken up positions on the land route in Beirut. Should it be decided these initial groups should go by sea instead of land, "this departure schedule also is subject to amendment."

* Aug. 26-28 (approximately) -- Remainder of the multinational force, including U.S., Italian and remaining French troops will arrive in Beirut and deploy to "agreed locations." PLO groups will continue to move to Syria by land or sea.

* Aug. 29-31 -- Syrian troops of the Arab Deterrent Force redeploy out of Beirut.

* Sept. 1-4 -- Departure of remaining PLO members destined for Syria. Assembly and departure by sea of all PLO personnel destined for the Sudan and Algeria.

* Sept. 4-21 -- Multinational force assists the Lebanese Army "in arrangements, as may be agreed between governments concerned, to ensure good and lasting security throughout the area of operation."

* Sept. 21-26 -- Departure of multinational force.