7 CFR 29.3021 - Fiber.
The term applied to the veins in a tobacco leaf. The large central vein is called the midrib or stem. The smaller lateral and cross veins are considered from the standpoint of size and color and in some types are treated as elements of quality. In Burley, fiber size and color are not of great importance, except where a fine distinction must be made between several lots of high quality or between sides of the same lot.