Mr. That's Enough, please meet Mr. Long March

In Vietnam, a name is often more than just a name.

For example, few foreign diplomats or government officials who have dealt with Vietnam's polished but tough foreign minister would be surprised to learn that Mr. Thach's name means ''stone.''

Vietnamese names can also shed some unexpected light on the bearer's background.

Most names come in three parts: first, the family name, which is of less significance than in the West since most Vietnamese seem to share from among six or seven of them; then the middle name ''filler,'' often denoting little more than the person's sex; and finally, the given name.

Nguyen Co Thach's name is an interesting one. It's clearly a pseudonym, and has a unique filler - Co - apparently meaning machine or engine. This perhaps harks back to the socialist belief in machinery and industrialization common a generation or so ago.

Although the name Thach is common, he might have been thinking of another revolutionary - the Russian Kamenev (whose pseudonym also means stone) - when he chose it.

Further down the social scale, a man named Nguyen Van Het was in the news recently. Without having met Mr. Het, one can guess that he is from a fairly humble peasant background and a large family. In fact, it is apparent that Mr. Het was intended to be the youngest: Het means ''that's it,'' or ''finished,'' and was often given to the latest child by a mother who had had enough of childbirth. Another common variation is Thoi, meaning ''that's enough.''

Vietnam's new ambassador to Moscow, Central Committee member Dinh Nho Liem, comes from a very different background from Mr. Het. His middle name tells us his ancestors were Nho Si, Confucian scholars.

Many of Vietnam's leaders have taken pseudonyms at various points in their careers - not an uncommon custom in Asia, but an especially good idea if you're trying to overthrow a government.

The real name of Truong Chinh, de facto head of state and the party's main theoretician, is Dang Xuan Khu. His pseudonym means ''long march,'' a relic of happier relations between Chinese and Vietnamese revolutionaries.

Perhaps the most subtle collection of names and pseudonyms belongs to what is probably the most powerful family in Vietnam today - Le Duc Tho and his two brothers.

Le Duc Tho, officially No. 5 in the Politburo, is thought by many to be the actual ruler of Vietnam today. Duc means ''virtue'' and Tho means ''longevity.''

His brothers, Mai Chi Tho and Dinh Duc Thien, have assumed different family names, though each has retained a part of his elder brother's name.

Mai Chi Tho, Central Committee member, mayor of Ho Chi Minh City, and some say, the security chief of southern Vietnam, keeps ''longevity.''

Dinh Duc Thien, dropped from the Central Committee this year after a distinguished wartime career, retains ''virtue.'' The other part of his name, Thien, means ''good,'' although he is famous for his hot temper.

One leader whose name is not supposed to be a pseudonym is Vo Nguyen Giap, the founder of the Vietnamese People's Army. It is ironic that the general's family name, Vo, often means ''weapon,'' and his given name, Giap, ''armor.''

As in most countries, names in Vietnam change with the fashion and generation.

If you read of a northerner called Nhan (benevolence), or Nghia (righteousness), you can be pretty sure that he was born before the 1945 August revolution. These are old Confucian virtues that lost ground during the war against the French and the United States to more martial names like Chien Thang and Viet Thang - ''military victory'' and ''Vietnamese victory,'' respectively.