WASHINGTON — Confusion over a petition threatens to curdle the dairy industry’s efforts around labeling flavored milk.

In a petition submitted four years ago, the International Dairy Foods Association (I.D.F.A.) and the National Milk Producers Federation asked the Food and Drug Administration to update its standard of identity for milk to include approved zero-calorie sweeteners as an option in sweetened dairy products. Current regulations require products containing such ingredients to be labeled as “reduced calorie” or “no added sugar,” but dairy manufacturers want the packaging to simply say “chocolate milk.” If non-nutritive sweeteners are added to the list of standard ingredients for flavored milk, the products wouldn’t require the front-label description that dairy manufacturers have deemed unattractive to some consumers.

According to the I.D.F.A., school-age children are turned off by “reduced calorie” labels. The industry hopes the proposed change would position flavored milk to compete with other beverages that contain non-nutritive sweeteners but aren’t subject to the same labeling restrictions.

Since its February publication in the Federal Register, the petition has drawn some negative feedback due to misunderstanding, said Peggy Armstrong, vice-president of communications for I.D.F.A.

Based on more than 30,000 comments received, the F.D.A. has attempted to address the confusion and educate consumers on the proposed change.

Some consumers are concerned that sweeteners would be added to plain milk. Additionally, some worry that dairy manufacturers will attempt to sneak ingredients into the product without including them on the package’s ingredient list. Neither presumption is true, Ms. Armstrong said.

“What we asked for is some flexibility as to what we can call it on the front of the packaging,” she said. “All ingredients would still be listed on the label.”

The confusion stems in part from the difficulty to describe the amendment of a food standard in plain language, said Arthur Whitmore, public affairs specialist in the F.D.A.’s Office of Food and Veterinary Medicine.

“In general, consumers are unfamiliar with the concept and requirements of a food standard,” Mr. Whitmore said.

The F.D.A. has published a clarification for consumers on-line and is inviting public comment on whether the proposed change will provide sufficient information for consumers to understand what is in the milk they buy, as well as whether the “reduced calorie” description affects their purchasing decisions. The item remains open for comment until May 21.