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 For 30 years we lived in a suburb of Minneapolis, where the largest and
best grocery stores are named Byerly's.  I believe there was a celiac in
the Byerly family, and the store made sure that the little  white plastic
pricing labels that were  on the front of the shelf under every product
were color coded.  Green strips meant NO GLUTEN.  The store administration
had taken the trouble to contact all their suppliers.  They also had a four
page hand out listing all gluten-free foods.  I don't remember the other
colors, but there were salt-free foods, diabetic safe foods, etc., all with
color coded labels and hand outs.
It should not be too hard to get other stores around the country to follow
their examaple.

Gayle Kennedy