Many of us go in for people-watching. But an acquaintance of mine is a true specialist: a briefcase-watcher. And she reports a very high incidence of bananas in the briefcases of us fast-lane folks who ride commuter buses into Washington, D.C. . . . even higher than that of apples.

I'm not sure of the significance of this simian-like preference. It apparently has nothing to do with either the current administration or the recent recession. But the bananas and the apples, along with sandwiches galore, certainly show that the briefcase often serves as a lunch box or brown bag in disguise.

For men, it has also become a socially acceptable purse. Without burdening our pockets, we can keep our antacids and allergy pills, train or bus schedules, spare handkerchiefs, eyeglass wipes, paperback books and other paraphernalia comfortingly at hand.

I'm convinced that, among males, that kind of use is now vying with the transport of paperwork as the commonest function of a briefcase. And usually the two are combined.

One result of all this is that the status value of briefcases (or attache cases, as the status-conscious often term them) has depreciated. They are so commonplace now.

For women, they still help proclaim that the bearer has more than a nine-to-five job. But really symbol-minded people, male or female, must concern themselves with the type of case they carry.

Leather is better than plastic. And a thin leather case is better than a thick one, implying that you read "executive summaries" instead of printouts or two-volume research reports.

An exception to this rule is a large but battered leather briefcase flaunting a British Airways or Air France identification tag. With a little luck you'll be taken for someone who makes sudden hops on the Concorde, supplied only with toiletries, a change of underwear, an extra shirt or blouse, socks or stockings, and enormous power.

One last tip: a high-status briefcase has a combination lock.

There are those, of course, who contend that the ultimate briefcase-upmanship is not to carry one at all. Like a clean desk, this is supposed to suggest that you're so lofty, well-organized and well-served by your staff that you're totally on top of your job.

Unfortunately, this ploy doesn't seem to work with those who don't know what your job is (or those who do, either)--unless you drive a Maserati or have a chauffeur. And if you're in that class, why worry about whether to carry a briefcase or what kind to choose?