Atmosphere: A neighborhood melting pot spiced with a good dash of urban flavor.

Price Range: Pick one and it's yours; from a 60-cent fried-egg sandwich to a combination seafood platter at $4.35.

Hours: Any day, from 7:30 a.m. to midnight.

Special Facilities: Accessible by wheelchair. Booster chairs. Street parking.

Reservations: Just walk on in.

Credit Cards: American Express, Master Charge, Visa.

It was a Sunday afternoon downtown, when so many of the streets look like test sites for neutron bomb target practice - everything's in place, but there's not a trace of people. That's a pleasant time to pad around in peace and quiet, if you know where to go when hunger sets in.

We found out where many an in-city dweller goes for unpretentious, hearty fare in the neighborhood around 17th and Q streets NW. On that corner is an ordinary-looking eatery called the Trio Restaurant - and therein hangs today's tale of family foraging.

There's nothing fancy about the Trio. Indeed, unless your idea of a bright spot is the second or third letter on a flickering neon sign, you might never drop in here. Inside, with its maze of booths and an L-shaped counter up front, the Trio looks at first glance like a cafeteria without a food line.

It's the second glance that gets you, though, for the clientele is what's interesting. At only a few minutes past 6 p.m., we thought we'd be early for supper, but already the place was bustling. Toward the back we found an unoccupied bare booth and the four of us slid in to check out the crowd.

It reminded us of those marvelous lunch spots in Manhattan neighborhoods, where the people-watching beats any floor show. So bug-eyed were our kids that they didn't even hear the loud whaps when a waitress plopped down four tumblers of ice water and some menus.

A quick panorama: Across the aisle, a gathering of bowl-of-chili student-types. Down the row, a man in suit and tie who came in with a raincoat and newspaper over his arm and is now eating behind the centerfold of the Business and Finance section. Here and there an infant or a toddler, and over in one corner, a cluster of older people swapping yarns.

"It's like this all day on Sundays," moaned the waitess, who seemed somewhat less enthralled than we were by the number of customers to be served.

So what about the food? We could tell right away that they must give some thought to the menu, because they print a new one each day. And the offerings, like the characters sampling them, include something for everybody.

Our kids were quick to note that the front counter is also a soda fountain of sorts, with those old-fashioned milk-shake mixers with the metal cylinder shakers as well as all the makings fo banana splits.

For 75 cents apiece, two chocolate malts were whirred up for the children; and for a dime more apiece, the parents secured malts of a different kind.

The rundown of complete dinners - that's with soup or juice, two vegetables, coffee, tea or iced tea and a snowball-sized poppy seed roll - came to 16 entrees from $2.70 to slightly under $5.

If that doesn't do it for you, there are innumerable offerings on the well-thumbed permanent part of the menu: a hamburger or fried-egg sandwich for 60 cents, two eggs for 95 cents, other sandwiches from $1.30 to $2.20, salads from 85 cents on up, chili at $1.20 or maybe a fried half-chicken with chef's salad and fries for $2.60.

After a round of chicken broth for three of us, our 11-year-old son, currently on a shrimp kick, applied for a jumbo fried shrimp platter and a double order of fries at $4.10. With the batter they use here, that's a solid helping of caloric cholesterol, but he relished every forkful.

His 8-year-old sister, meanwhile, was busy strip-mining a mountain of spaghetti with meat sauce, $1.90. She liked it, and so did I when summoned to help out.

Like those shrimp, the fried oysters at $3.30, selected by my wife, were heavily battered but unbowed. Anyway, there's an "R" in the month, just as there is in the word "freezer" where these fellows were found.

In selecting the sizzling steak at $4.25, I got more sound than substance. The sizzle, by the way, is really the noise made when the meat starts sticking to the metal plate. With it came fried onion rings for my companions and fried potatoes for me.

The desserts run from 40 cents for pudding, jello and ice cream to 50 cents for pies and 90 cents for cheese cake. But after all that food and the malted milks, none of us was in the running. That brought the bill for everything in at a reasonable $18.37 plus tip.

For solid fare, served up with a pleasant slice of downtown life, the Trio filled the bill for us quite handsomely.