AR 670-1: Chapter 13: Blue Service and Dress Uniforms ...
For accessories and other items authorized for wear on the Army (blue) service Class B uniform, see paragraph 13–11, below. (3) The Army (blue) dress uniform includes the Army blue coat and trousers, a long-sleeved white shirt, and a black four-in-hand tie (before retreat) or a black bow tie (after retreat).