As Deng Xiaoping turns 90, attention focuses less on his decisions than on his death - when it will come and what will happen to China afterward.

Since Deng took over in the late 1970s, after decades of upheaval, China has enjoyed relative tranquility and prosperity.The authorities seem determined to make sure the stability survives Deng's departure, but China's political history suggests anything could happen.

Rumors of Deng's actual or imminent death arise regularly and wreak havoc on Asian stock markets, but a Western diplomat said last week: "I've consulted our highest authorities and they think he'll make it through his birthday" on Monday.

While the birthday is unlikely to be marked in an official way, there have been signs of its approach.

Stores are selling Deng medallions with an inscription translated into English as "Our general designer. Comrade Xiaoping Deng." A two-volume biography, "Deng Xiaoping's Life: A Great Man and His Century," arrived at bookstores this month.

Official media are filled with reports of the masses earnestly studying Deng's theories, which in 15 years have transformed China from an inward-looking, impoverished nation to a major power.

About Deng's activities, however, there is virtually no information. Government officials will not divulge anything, they say, because he is just a private citizen who holds no office.

His children occasionally offer the standard line that their father is in good health, but nothing more.

The only national publication known to have mentioned the impending birthday was the China Aged Daily, which printed a front-page photograph and short profile of Deng on Wednesday.

It quoted him as saying, "I can swim. That shows that my health is still good. I play bridge, which shows that my mind is still clear."

No date was given for either the interview or the photo, which makes Deng look hale. In his last public appearance six months ago, he seemed feeble and dazed.

Many people who follow China closely feel the impact of Deng's death will decline as he hangs on.

"All the signs seem to be that Deng, apart from certain key decisions, doesn't function in an effective way," said Gerald Segal, a noted scholar of Chinese affairs.