Back in September of 2008, a petition was submitted to the FDA to include rye and barley in the list of most common allergens which must be disclosed on packaging. Right now, only wheat has to be disclosed, but as we all know the gluten of rye and barley is just as offensive to celiacs as that of wheat. So to include wheat in the list without including rye and barley was nonsensical. The list needs to be amended so that rye and barley sources are also disclosed.
Without this disclosure, such things as "modified food starch", "flavor," "natural flavor" and other ambiguous ingredients may be derived from rye or barley without disclosure. This means that currently we cannot buy or eat anything with such "ambiguous" ingredients without a great deal of risk. After a 6 month delay, the petition is now available to be seen and publicly commented upon at:
http://www.regulations.gov/fdmspublic/component/main?main=DocketDetail&d=FDA-2008-P-0509. Despite what this website might say, it is not an expired petition, and you can comment on it.
I hope you will go there, and read the petition, and leave a comment in favor of it for the FDA's consideration. The more positive comments we get stored in FDA's database, the sooner we are likely to get action on this.