The celebrations last month of the 15th anniversary of Correctionist Day, the Syrian national holiday that marks the ascension to power of President Hafez Assad, was an occasion for a rare display of public demonstrations in the cities and towns of this militarized nation.

Buildings in the capital and the provinces were dressed up with strings of lights and giant paintings of the stern, graying president. For weeks the state-controlled newspapers were full of reports about the cables pouring into Assad's office endorsing the "correctionist movement" he led to power in 1970 and the texts of the president's speeches sent to be read in his name before various national groups.

Under the wary eyes of the muhabarat, the secret police who sit at major city intersections in white Volvos with automatic rifles on their laps, rallies were held in which thousands of school children, civil servants and members of the ruling Baath Party marched to patriotic songs, carrying national flags and holding aloft hundreds of placards with identical pictures of the president.

Damascus, the dour, ancient Syrian capital, was even treated to a rare fireworks display that colored the night sky at the height of the anniversary festivities.

The only thing lacking in the celebrations was the presence of Assad. At 55, the former Syrian Air Force commander, who has surprised many by giving formerly coup-ridden Syria its first stable government since the nation's independence from France in 1946, made no public appearances, thus reviving speculation about the continuing fragility of his health in the wake of a heart attack two years ago.

The difficult question also has been raised as to who would rule Syria if Assad were to die. His health is one of the many subjects that are taboo for public discussion -- along with Israel, neighboring rival Iraq and the fundamentalist Moslem Brotherhood that for years has challenged Assad's secular rule over Moslem Syria.

Nevertheless, merchants in Damascus' famed covered souk, or street market -- men who through the centuries have been the keenest observers of the governments on whose policies their wealth or poverty depend -- now speculate readily in the back rooms of their shops about the signs of Assad's seemingly waning strength.

"If Assad were healthy he would have appeared in public for the anniversary of his 15th year," said one shopkeeper, insisting that his name not be used. "That he has not appeared means that he is not as well as the government says."

That is a judgment readily supported by foreign observers who, in the nature of their work, have occasion to come into contact with Assad.

"He has days when he is capable of mentally strenuous work, holding five-hour work sessions without tiring," said one senior diplomat in the capital who has watched him. "But there are other days when he looks like hell."

But despite evidence that he has never fully recovered from the heart attack, no one questions that Assad remains very much in control of Syria. Although his illness in 1984 set off a potentially explosive succession struggle that had rivals for Assad's job -- including his brother Rifaat -- mobilizing their troops in the streets of Damascus, today none of the president's rivals has lifted a finger to assert his claims on the future.

"What is interesting is that despite signs that he is not well," one western diplomat here said, "his command and control of Syria is beyond question. How long that will remain, however, is anyone's guess. He is a man of 55 who looks 10 or 15 years more than that."

What interests foreign analysts here is that all of the men who were involved in the 1984 succession struggle, when it was thought Assad was close to death, remain potential players in the next round, although some, like Rifaat Assad, have had their powers checked.

The 1984 power struggle was first of all a struggle within the president's own minority Alawite Moslem clan, between his younger, impetuous brother, Rifaat Assad, then commander of the Defense Companies -- the palace guard -- and other members of the president's extended family and Alawite chieftains in the Syrian Army.

In what is now understood to have been a move to claim the right of succession from his brother, Rifaat Assad mobilized his heavily armed Defense Companies in the capital in 1984, sealing off key roads into the city, while a leading rival, Gen. Ali Haidar, who is Rifaat Assad's brother-in-law, put the Special Forces he commands on alert to counter him. Another brother-in-law, Gen. Shafiq Fayez, commander of the 3rd Armored Division, meanwhile mobilized his tanks to the west and north of the capital in support of Ali Haidar.

The confrontation lasted about 30 hours and ended mysteriously with all units standing down, apparently because Hafez Assad became aware of what was happening and ordered an end to the rivalry. He then packed all three men -- brother Rifaat, Ali Haydar, and Fayez -- into the same plane to go to Moscow as part of a military delegation.

The two generals eventually returned to Damascus to their old commands while Rifaat Assad was sent to Geneva in what seemed at the time as official exile. But he too eventually returned to Damascus, although not to his old command of the Defense Companies.

When Rifaat Assad returned a little more than a year ago, the betting here was that he was finished, having overplayed his hand and embarrassed his brother by his seemingly hasty grab for power. That judgment, however, has been tempered recently by signs that Rifaat Assad is still not to be counted out of Syria's future.

For most of the past year, Rifaat Assad camped in the Assad clan village of Qardaha, holding court for a stream of visitors and, according to one western diplomat, "mending his fences in the Alawite community."

This fall, still one of Syria's three vice presidents, he moved back to the capital in time to host Saudi Crown Prince Abdullah on a visit to Damascus to encourage -- successfully it turned out -- a reconciliation between Hafez Assad and King Hussein of Jordan. Rifaat Assad, who is married to a sister-in-law of Abdullah, has long been the Saudi government's main interlocutor with Hafez Assad.

More significant in the overall power equation, many diplomats believe, is the surprise marriage last summer of Rifaat Assad's daughter to Fayez' eldest son -- a move that many analysts here say may be a sign that peace has been made between at least those two important rivals.

Some diplomats here feel that Rifaat Assad remains out of the picture because he has lost command of the troops that gave him power. That view, however, is not universal and many other analysts point out that he still has his brother's patronage, Saudi support, probably new ties to the Alawite community and, in a pinch, could still command the loyalty of officers who once served under him.

"I think Rifaat remains very much a player in the succession sweepstakes," one ambassador here said, asking that his name not be used. "Everything is still very much up for grabs."

Rifaat Assad remains anathema to Foreign Minister Abdul Halim Khaddam, who is also a vice president, and Defense Minister Mustafa Tlas, who last year told a West German news magazine editor that if Rifaat Assad had not left Syria last year after the power struggle, the Army would have forced him to leave.

Khaddam and Tlas are both powerful men in President Assad's government but they are also Sunni Moslems in a government where all key posts in the military and intelligence services are in the hands of the minority Alawites of Assad's clan. Thus it remains unclear how much of a say they would have in choosing a successor.

What would happen if Hafez Assad is forced out of office because of his health remains a hotly debated question here.

"The fact is that there is no real clearcut successor in sight," one western diplomat said. "Hafez Assad is so strongly number one that he has not let anyone emerge as a real number two. Whoever it is would have to be an Army man and Alawite, which would seem to preclude Khaddam and Tlas. But given the rivalries of last year there is evidence that the Army and the Alawites are unified in their choice and that could mean trouble -- and a return to the instability Assad's rule ended."