It was planned, and the plan was the most important part. The junta was harmonious. The junta was predictable. On Sept. 29, according to a schedule that has been drummed for months into the Argentine public, the junta was to end its deliberations and announce, officially, the name of the new president.

Unofficially, everybody already knew -- or thought they did. The selection of Gen. Roberto A. Viola, former Army commander-in-chief and close associate of current President Jorge Rafael Videla, was so widely expected that it had become something of a national joke. There is an Argentine song in which you indicate the identity of your chosen love by singing the first letter of his name. In a newspaper cartoon, a radio was playing the song with the letter V. And people passed around a one-liner in which an official, asked to leak the selection in advance, replies, "That is a secret that must not be Viola-ted."

Came the 29th. No word.

Came the morning of the 30th. No word. Then, midafternoon Tuesday, a terse communique came from the office of the military junta. The announcement of the new president -- scheduled to take command of the military government next March -- would be delayed 10 days.

If you wanted one strong taste of Argentine political life today -- both the reality and the elaborate rhetoric -- you might have stood yesterday morning on a rain-slicked Buenos Aires sidewalk, watching uneasy businessmen with black umbrellas tuck bold-headlined newspapers under their arms.

The postergacion (postponement) is the biggest story in town. The news bulletined out on the radio. Brokers at the stock exchange ran to the press room to see if it were true. Sales dropped in the second half of the day. The city is awash with rumor. An Argentine intellectual, almost smiling as he pulled on a trenchcoat to head out into the spring rain, said, "It's starting to feel like Argentina again."

What that means is that factionalism, open speculation and public doubt are cracking the smooth institutional facade of the military junta that has governed since 1976. The delay in the presidential announcement, according to the most persistent political rumors is the result of deep conflicts among the armed forces -- long-existing but never made public, particularly between the Army and Navy -- over the direction of the economy, the distribution of ministries and governorships, and the nature of the presidency itself.

The president, under the current arrangement, is supposed to answer to the junta, which is composed of the commanders-in-chief of the Army, Navy and Air Force. The line, officially, is that the junta sets policy and the president is given some leeway in which to implement that policy.

As far as most Argentines are concerned, only one policy really matters right now -- the dramatic and enormously controversial "opening" of the economy by Finance Minister Jose Martinez de Hoz. He has insisted that Argentine business adapt to an international competition that opponents say is killing it.

Martinez de Hoz has always been Videla's man, and Videla is an Armyinter man -- if a bland one, with a tendency to look perplexed and apologetic when foreigners criticize his government's human rights record.

Although there is no indication that Gen. Viola is himself an issue in the junta's debate, it is widely believed that the members are still arguing over how much economic control the new president will have.

But it is the sudden surge of political curiosity and interest since the postergacion that most jolts the stranger -- and says so much about the Argentine political myth and reality.

A week ago, if an American had asked a Buenos Aires shopkeeper or taxi driver what he thought about the presidency, he was as likely as not to say Reagan stood a pretty good chance. And what about Viola, you would ask -- what is known about him? There would be a pause. A "moderate," he would say. "Fended off the far right wing of the military. More likely to open real dialogue with the political parties."

The voice would be bland. Viola's reputation as a moderate has reportedly made him somewhat controversial within the military, but in the streets he stirs no passion. In his photographs he looks like a short Charles de Gaulle, with a white moustache.

This is a nation battered by the times, and in the eyes of most Argentines it has made a massive bargain -- it traded politics for order.

It is not that Argentines like or dislike Viola. The choice of a new president is simply none of their business. The president was being chosen as part of the Process. The Process is institutional. The Process replaces political noise here. No crowds call the name of a man who will lead them, perhaps astray. The nation is to be saved from "sectarianism, factionalism or personalism."

The quotation is from Basic Documents of the Process of National Reorganization, the stapled white booklet that contains the official guiding philosophy of the military junta that took over in 1976.

Very few Argentines have ever sat down to read it, but the booklet has become the most important public document. Every change -- economic educational, social, political -- has been explained, packaged, publicly justified as part of the Reorganization Process.

Argentines take conserable pride in their ties to Western Europe, their traditional love of international theater and music, their European immigrant ancestry -- so much pride that you will hear a Peruvian or a Mexican gnash his teeth over those smug and self-centered Caucasians in Argentina.

But democracy has rarely worked here.There are as many explanations why as there are political factions. It is argued that the pervasiveness of early international business dealings, often geared to trade with Great Britian, created a nation too dependent to establish a geuinely national business strength.

It is argued that the military, by long tradition in Latin America a professional class that sees its interests as purely and apolitically national, was always too ready to intervene when the government teetered. This is said to have created a vicious circle in which elected officials abandoned moderation, knowing they could abdicate to a waiting military.

And it is argued -- especially by the economists, politicians and officers most adamantly opposed to a return of the enigmatic political phenomenon called Peronism -- that during Juan Domingo Peron's first presidency, from 1943 to 1955, the army colonel and his powerful young wife nearly dismantled Argentina.

By the time the current junta took over, the government had changed hands 12 times in 25 years and the second Peronist era clearly was near collapse. To a nation beset by violent dissension, hyperinflation, a terrorist left, a terrorist right, and routine bomb attacks on the public streets, the junta presented its program for what it declared would be the permanent restoration of order: the Process.

There would be no more instability. The junta would create a whole new society: Christian, moral, antisubversive, secure, with a restructured economy and an educational system designed "to meet the nation's needs."

The commanders would do this calmly, methodically -- institutionally. There would be no Peron, no single passion-inspiring individual leader, to delfect the course of the Process.

Then, eventually, they would go away.And democracy, they declared, would work.

The Process dissolved congress.

The Process susupended political activity. The Process banned membership in certain political parties and allowed continued membership in others.

The Process is not by any means universally accepted. There are many here, and others in exile, who believe the military has no intention of ever reviving democratic rule, that the Process is just an ideological justification for a violent suppression of the left.

There are a lot of Argentines who believe that while the military "moderates" like Videla want to call elections they cannot let go until the country somehow gets past three questions:

How will the military account for thousands of persons "disappeared," apparently killed, in the battle against "subversion"? What is the future of Peronism? What will become of the economy, still running one of the world's highest inflation rates?

But the Process is the packaging of power in Argentina today. Every public political move -- the carefully scheduled departure of Videla, after what will be five years in the presidency, the regular shifts of commanders-in-chief, the impending appointment of Viola -- is part of the institutional, orderly and public face of the Process.

And that may be why the slipup signified in the delay of Viola's appointment, even if it is a minor matter, has caused such a stir in Buenos Aires.