The "Type A" school lunch, served to 26 million children throughout the country including more than 250,000 in Washington area, may soon undergo some substantial changes under new regulations proposed yesterday by the U.S. Department of Agriculture.

The new rules would reduce the amount of meat, milk, and vegetables that must be served daily to most young children attending public schools. They would also end the requirement, dating back to the program's start in 1946, that every child must get one slice of bread a day no matter what else is on the menu.

Under the new system children would get 8 to 10 servings per week, depending on their age, of either bread or a starchy bread subtitute, such as rice, noodles or spaghetti.

Agriculture Department officials said they hoped the new rules would reduce waste, which now amounts to about 15 per cent of the food served daily. They said they also hoped there would be more variety, including enough flexibility so that local schools could serve foods that are particularly appealing to specific ethnic groups.

In Washington Joseph Stewart, director of the D.C. school system's food service program, said he was "glad to see the changes. It's good to have more flexibility." But Stewart said the requirement of giving smaller portions to children under age 9 will cause "some logistical problems" because it will force schools to serve two different-sized meals in the same lunchroom.

The problem won't be too difficult, Stewart said, in schools with their own kitchens and cafeterias. But he said about a third of the 64,000 D.C. children getting school lunches each day eat frozen "pre-plated" means served in aluminum-foil trays, because their schools do not have cafeterias.

"There'll have to be two production lines to take care of the two different amounts," Stewart said, "and then we'll have to keep the stock separated, and serve it separately. That means more problems."

Like hundreds of school districts around the country, the D.C. school system buys its frozen lunches from a contractor. Last year it was Morton Foods.

In Prince George's County, which cooks all its school lunches, food service director C. Anthony DiMuzio welcomed most of the proposed changes but said he was "a little apprehensive" about the new portion requirements.

"In some elementary schools they pair off the first graders and the sixth graders so the big kids can help the little ones," DiMuzio said. "Now we'll have to give out different portions to the two groups, and that's going to slow up the line. We'll have to see how it works out."

Under the "Type A" rules all school lunches must have a minimum each day of 2 ounces of meat or an alternate, 3/4 cup apiece of two fruits of vegetables, 1 slice of bread, and 8 ounces of milk. The new rules would cut the serving sizes for children under age 9 to a half cup for fruits and vegetables, 6 ounces for milk, and 1 1/2 ounces of meat.

The serving sizes would stay the same for children aged 9, 10 and 11, and would be increased 12 and above, but older children would be allowed to take less food if they want to.

Agriculture Department officials said the proposed changes would be tested in some districts from January through April next year before definate new requirements are issued.