Urwin, Gregory J. W. The United States Infantry: An Illustrated History 1775-1918.London: Blandford Press, 1988. U.S. Army uniform regulations define a class of "special ceremonial units" (SCUs), which include guards units and bands, that are authorized to wear distinctive uniforms – in lieu of the Army Service Uniform – for public duties, including state arrivals, official funerals, change-of-command and retirement ceremonies, and the presidential inaugural parade. d.write('