Open Tuesday through Friday, 7 a.m. to 9:30 p.m.; Saturday and Sunday, 9 a.m. to 9:30 p.m. MC, V. Reservations. Prices: Main courses at dinner average $4. A three-course meal including wine, tax and tip, can be less than $10.

If you were in Washington in the '50's, you knew of the Woodner apartments as the last word in residential splendor - the acres of lobby leading to glass-walled corridors overlooking Rock Creek Park, Buicks and El Dorados issuing crinolined ballgowns for the dances. You also knew of the AV Ristorante across town, where real homestyle Italian cooking was being introduced to diners hungry from hours of jitterbugs and chachas. Now it has all come together in Fio's restaurant, a kind of breathing museum that has ensconced the old chef of the AV in the vast old coffee shop of the Woodner. Fio's is a period piece, a representation of the '50's, from the curved pink Formica counter that snakes through its center, to the price of the antipasto ($1.50) and the scaloppine marsala ($4).

On a Saturday night, Fio's has the ambience of a Greyhound bus station in full dress. At that pink Formica counter are women of untold decades dressed and made up for an evening on the town. One corner is sectioned off by ornate metal fencing and turned into a Mediterranean nook by a pastel mural. The tables around this island are a sea of burgundy vinyl cloths set with assorted candles - purple, blue, any old color - dripping freeform sculptures onto their holders. A juke box alternates the Platters and Mario Lanza.

Here it is, the mythically correct setting for pizza of heroic quality, homemade pastas of unsung glory, veal dishes of noble character, the myth being completed by the peasant prices.

A waiter in jeans - maybe with a jeans jacket if it is Saturday night - recites a list of the daily specials: roast veal, roast duck, Cornish hen, a couple of fish or seafoods. While the bar looks designed for a Hollywood extravaganza with its tiered displays and mirrors, the wine possibilities are limited to red, white and rose, usually a decent Spanish jug wine, at 85 cents a glass, $2.50 a half-carafe. With a loaf of bread, which is good chewy Italian stuff, the mood is established.

The real eating can start with antipasto, a plate of greens with snippets of several Italian cold cuts, cheese, olives and cruets of oil and vinegar; or with melon and prosicutto at the same startling $1.50. The soup is fairly good. Or you can head right into pastas, the full range including lasagne, manicotti, cannelloni, ravioli, tortellini, and gnocchi among the homemade noodles, costing $3 to $4 for what many restaurants around town are charging double. This is assertive Southern Italian food, and the tomato sauces are the best of the kitchen, being meaty and chunky and intensely flavored. The stuffed noodles stand up well to the sauces, and the lasagne is a treasure of fresh mushrooms and ricotta and stringy cheese. Don't waste your visit on cream sauces or the likes of fettucine Alfredo.

You could also start with pizza - $2.50 for medium, $3.50 for large - but it would be too hard to wrench yourself away from it to go on to meat and fish courses. It is yeasty, chewy pizza with the earthiness of good bread, topped with a light wash of tomato chunks and cheese, plenty of herbs and olive oil. Canned mushrooms or warped little rounds of sausage don't enhance it, so order it plain. It is pizza that would make anyone's list of bests.

Traditionalist AV fans inevitably order the meat platter or fish platter, and those who order the meat ( $5) will recognize that the clock can indeed be turned back. It is as big as one remembers, with spicy braciola stuffed with ground meat and hard-cooked eggs, tomato-tinted chicken cacciatore, eggplant parmigiana and a big chunk of sausage. The fish platter - same price but less voluminous - swims in a delicious sea of fish stock, garlic, pepper and oregano, but the five mussels, three clams, single shrimp and section of king crab were less than impressive. The menu lists a full range of veals - scaloppine pizzaiola, al burro, marsala, cutlets in several styles, osso bucco and saltimbocca, not all of which are available every day. But the veal is excellent tender pale meat, cooked with care, and sauced with deft spicing. At $4, the veal dishes are remarkable. There are also steaks, pork and lamb chops, shrimp and clams or mussels, also at $4 to $5. But the specials deserve special attention; roast veal, lamb shanks, whole flounder or trout to bone yourself, or roast duck sometimes miss with overcooking here or there, but in general they are huge portions of robust food, straightforward and very good. With them come the most memorable part of the meal, vegetables such as broccoli that has absorbed the aromas of garlic and olive oil, or cabbage sauteed with butter and plenty of black pepper, perhaps sauteed peppers and mushrooms. You could substitute an indifferent salad, or spaghetti with light, zesty tomato sauce. And you ought to splurge on a side order of fried zucchini, the thin slices lightly battered and still crisp, to be doused with lemon as you eat them.

False notes are few. Service, though it is exceedingly pleasant and patient, may lag if the dining room is unexpectedly busy, and orders are sometimes confused. Soft drinks cost as much as wine, but coffee is 35 cents for American, 60 cents for fine, strong espresso. Since the portions are large, you need not find out that the desserts are clumsy. Spumoni and tortoni are commercial brands, cannoli are oversweetened and heavy, and zabaglione was overcooked when we tried it. But Fio's serves food with no pretense of refinement or delicacy. It is hearty and homestyle, and the light touch is where it counts - in the pricing.