There are many pitfalls to a successful and prompt ceasefire in Zimbabwe-Rhodesia.

The plan is simple enough -- assemble the warring armies at various base camps and reception centers and impound their arms.

But before that can be done, the combatants must be identified and located and that will be difficult. The main combat forces of the Salisbury government will pose no problem in those terms. They are a conventional military organization operating out of five major bases -- Salisbury, Fort Victoria, Umtali, Bulawayo and Gwelo.

But the two guerrilla armies of the Patriotic Front -- ZIPRA and ZANLA -- are dispersed in teams of two to 10 men in hundreds of villages and caves all over the countryside, in an area half the size of Texas. A few wear camouflaged dungarees made in Ethiopia, East Germany or the Middle East.

A few identify themselves with denim jackets embroidered with slogans and nicknames -- "The Hungry Tiger for Mabunu [white South Africans]," "The Hungry Killer Who is Thirsty for Blood," "Son of Thunder."

But the vast majority are indistinguishable from the black civilian population. No one knows how many of them are in the country.

Intelligence officials in Salisbury put the number at about 15,500 early in November -- 12,000 ZANLA troops and 3,500 ZIPRA troops.Other estimates go as high as 30,000. In addition there are an estimated 17,000 ZIPRA guerrillas in Zambia and several thousand ZANLA troops in Mozambique, all of whom move rather easily back and forth across the borders.

Identifying and assembling these people will be an extremely difficult task.

The same is true of the thousands of "irregulars" roaming the countryside. Abel Muzorewa, the current prime minister of Zimbabwe-Rhodesia, has created a "private army," known as the "Spears of the People." Its size is estimated at more than 20,000 men.

Other politicians have their own "private armies." Thousands of black farm workers have been armed and organized into unofficial "militia" forces under the direction of white farmers. Up to 40,000 boys and young men called mujibas , most of them supporting the guerrilla forces, have become a force in the vast tribal reservations.

Many are simply hoodlums who terrorize villagers with real weapons or realistic wooden copies of the AK47 rifle. Others are valuable intelligence-gatherers for the two sides.

Finally, the country's 200,000 whites own more than 150,000 registered handguns, machine guns, rifles and shotguns.

The job of sorting all these people out will fall, under the British cease-fire plan, to about 1,200 Commonwealth troops who are unfamiliar with the terrain, with the contending forces and with the nature of this war.

One of the provisions of the plan is the withdrawal from the country of all "foreign forces." That provision presumably is aimed at South African regular troops in the country.

But a number of South Africans fighting with the Salisbury forces are identified as regular Army "volunteers," have been incorporated into regular units and wear the regular Zimbabwe-Rhodesian uniform. They will have to be identified and, if they are serving under false colors, presumably deported.

How the American, Canadian, New Zealand, British and Australian volunteers will be treated is unclear.

The definition of a cease-fire violation is likely to cause problems, too.

There are thousands of land mines all over the country, planted by both sides. If they cause casualties during the cease-fire will a violation have occurred? There are thousands of miles of border with Zambia and Mozambique. How will infiltration be monitored and defined? Will clashes between civilians and irregulars constitute cease-fire violations?

These are some of the issues yet to be resolved.