Based upon my experiences performing security cooperation duties in the Military Assistance Program (MAP) in Jordan, at a GCC, and at DISAM, I offer some thoughts and comments concerning the SDO/DATT concept.
No. Barley is not wheat at all. Barley and wheat are two different species of cereal grasses belonging to the family Triticeae. Barley does belong in the wheat family, which is, as mentioned, Triticeae, but is of an entirely different species from wheat. The species name for barley is Hordeum vulgare, and the species name for wheat is Triticum aestivum. No doubt either look similar, but both are quite different from the other.
In 2005 barley ranked fourth for cereal production (see Gramene Cereals). There are many types of barley, many different uses for it, and a long history of its importance to mankind. Cultivated barley is a member of the genus Hordeum. Cultivated barley is descended from wild barley (Hordeum spontaneum) (12, 13), which still grows wild in the Middle East (12).