Meslin is a mixture of wheat and rye grown and harvested together. Flour milled from meslin is classified under 1101 alongside pure wheat flour. If rye is milled separately and then blended with wheat flour after milling, the resulting product may fall under a different heading depending on its composition.

Imported wheat flour is a food product subject to FDA jurisdiction. Importers must submit prior notice of arrival through the FDA's Prior Notice System Interface, and the product must comply with FDA food safety regulations including labeling and adulteration standards. FDA may detain shipments that appear to violate these requirements pending further examination.