The question Dire Straits is asked most often is the one they like the least: "Are you surprised by your sudden success?"

Singer-composer Mark Knopfler shrugs, and rolls out words in a thoughtful caterpillar tread. "I don't really believe in definitions. They seem to me to be the lines people draw for themselves."

Still, the question is inevitable.Since the release of their debut album in Europe last June, they have been No. 1 in France, Germany, Holland, Australia and New Zealand, climbed close to the top in Denmark and Sweden, and are beginning to sell in Greece and Lebanon. And in America, only six months after a nearly unheralded release,the album is no. 4.

Although only No. 14 in their native England, in the U.S., where media interest is the measure of success, they are hitting faster and harder than any British group since Led Zeppelin in 1968.

But they have turned down television interviews, nixed "The Midnight Special," and politely indicated to "Saturday Night Live" that they'd rather wait until the second American tour in the fall. In general, says Knopfler, he thinks American television is "diabolical."

And he feels a kind of "horrified fascination" for TV commercials, the kind that "break up Shakespeare to say, 'Come with us into th world of shock absorbers and scouring pads and Boston scrod.'"

He pauses, a journalist-turned-English teacher shuffling words into a squre deck. "American television does not allow for a break in conversation, or a pause for reflection. Everything's edited down, so that each encounter becomes a welter of words, and meaning becomes dislocated."

The stars' diffidence is not their only anomaly. Their restrained, swing-flavored, blue-bottomed rock (epitomized by the hit single, "Sultans of Swing") is wholly unlike the herd of British punk and New Wave rockers. Labeling their sound is so difficult -- and Knopfler resists labeling so strenuously -- that like-minded bands in Britain have taken to saying they play "dire straits."

And that leads to another of their most-frequent, least-favorite questions: "What do you think of punk music?"

Knopfler shrugs again, his equanimity impenetrable. "It's just like the 1950s. Ther's some blues in it way back, and even some country blues... Like in 1957, 'It's a Bad Neighborhood,' Ronnie and the Delinquents -- that's a real punk record.

"Billboard and all the trades, they have all these definitions, disco charts and country charts and rock charts and AM and FM. It's not the business of music people, no my kind of music people, to worry about all those categories."

The myth of the liberating punk angst -- the image of the British lower class ground between the economic millstones until only the rich and famous escape -- has little relevance for Dire Straits.Before the group's breakout, Knopfler was lecturing at a London Educational college; his brother David, who plays rhythm guitar behind Knopflr's lead, was a social worker. Bassist John Illsley was working toward a sociology degree, and Pick Withers was trying to make a living as a drummer.

"We do it to make people feel good," says Knopfler, absently chewing on a fingertip as cigarette smoke masks his eyes. "The enduring good feelings that we get are the result of being on people's shelves because they want to have the record and play it. If you want to be a writer, you want to be published."

This five-week tour of America has been a revelation to Knopfler, not just the audience response -- the entire tour sold out in advance, and Dire Straits broke the Bottom Line attendance record held by Bruce Springsteen -- but all the plastic-and-platinum aspects of American culture.

In Willimantic, Conn., he says, the group "perforce" experienced their first Big Macs. The waitresses later sent them a note saying "we were proud to serve you." In Boston they rented a car which poured water from a defective door all the way to New York. They take trains between cities as often as practicable -- not for the romance, but for the relaxation.

They think American newspapers are "beauriful," the pizzas "enormous," the standrad of restaurant service superior and the country itseld full of space, energy and sense of humor as sophisticated as the British.

Knopfler sighs happily."The waitresses and hatcheck girls are amazing," he says out of the blue. "That's what I love about America."