WASHINGTON — The U.S. Department of Agriculture has submitted its proposed rule for foods sold in schools that are outside the purview of the National School Lunch Program (N.S.L.P.) to the Office of the Federal Register for publication. The so-called “Smart snacks in school” proposed rule draws on recommendations from the Institute of Medicine and existing voluntary standards already implemented in some school districts.

Under the proposal, any food sold in schools must be a fruit, vegetable, dairy product, protein-based food, whole-grain rich, or a combination food that contains at least a quarter cup of fruits or vegetables. Or, the foodstuff must contain 10% of the daily value of a nutrient cited as a public health concern in the 2010 Dietary Guidelines for Americans, such as calcium, potassium, vitamin D or fiber.

A product’s total fat content must be less than 35% of calories, while saturated fat must be less than 10% calories and it must have 0 grams of trans-fatty acids. Exemptions are provided in the proposal for reduced fat cheese, nuts and nut butters without other ingredients and seafood with no added fat.

Snacks must contain less than 200 mg of sodium, and non-N.S.L.P. entrée items must have less than 480 mg of sodium. For total sugar levels, the proposal features two alternatives: less than 35% of calories or less than 35% of weight. Exemptions to the sugar proposal are provided for fruits and vegetables packed in juice or extra-light syrup and for certain yogurts.

Snack items may have a limit on calories of less than 200 per portion while non-N.S.L.P. entree items will have a proposed limit of less than 350 calories.

The proposal also states schools may sell plain water, plain low-fat milk, plain or flavored fat-free milk and milk alternatives permitted by the N.S.L.P., and 100% fruit or vegetable juice. Portion sizes of milk and juice vary by the age of students. Elementary schools may sell up to 8-oz portions. Middle schools and high schools may sell up to 12-oz portions.

The U.S.D.A. proposal offers additional beverage options in high schools. They include 20-oz servings or less for calorie-free, flavored or unflavored carbonated water and other 7 calorie-free beverages that comply with the Food and Drug Administration standard of less than 5 calories per serving.

Additionally, the proposal would allow 12-oz servings of other beverages within a specified calorie limit. The proposed rule offers two alternatives for the limit: The first is less than or equal to 40 calories per 8-oz serving, and the second is 50 calories per 8-oz serving.

The rule also explicitly states such beverages shall not be available in the meal service area during the meal service periods.

The Centers for Disease Control and Prevention recently issued a report that analyzed state policies for food and beverages served outside the school lunch line that noted that 39 states already have a state law, regulation or policy in place related to the availability of snack foods and beverages in schools. In many cases, local level policies and practices exceeded state requirements or recommendations. The U.S.D.A. said its proposal would establish a national baseline of the standards, with the overall goal of improving the health and nutrition of children.

“Good nutrition lays the groundwork for good health and academic success,” said Secretary of Agriculture Tom Vilsack. “Providing healthy options throughout school cafeterias, vending machines, and snack bars will complement the gains made with the new, healthy standards for school breakfast and lunch so the healthy choice is the easy choice for our kids.”