The <i>kDB</i> system, consisting of the propagation vector <b>k</b> and the plane perpendicular to <b>k</b> and containing the field vectors <b>D</b> and <b>B</b>, is developed to treat electromagnetic waves in anisotropic and bianisotropic media. In using the <i>kDB</i> system, we first transform from the original coordinate systems to the <i>kDB</i>, determine the characteristics of the normal modes, and then transform the results back to the original coordinates.
J. A. Kong, "Optics of bianisotropic media," J. Opt. Soc. Am. 64, 1304-1308 (1974)