1H‐ and13C‐N.M.R. Spectroscopic Investigations of Substituted 1, 1‐Dioxo‐1, 2‐thiazines; Additivity of the Substituent Effects.The influence of various XCH2substituents (X: Cl, Br, I, SCN, SO2CH3, SC(NH2)2⊕, Py⊕) in the 3‐, 5‐ and 3, 5‐position of the 1, 1‐dioxo‐2‐phenyl‐1, 2‐thiazine on the1H‐ and13C‐n.m.r. chemical shifts of the ring atoms is described. The substituent effects are additive. The1H‐ and13C‐n.m.r. chemical shifts of the 3, 5‐substituted 1, 1‐dioxo‐1, 2‐thiazines can be calculated from increments d