Lee, LiTits, A.L.Continuity/discontinuity of robustness indicators is reviewed. For the case of real or mixed uncertainty, a regularization of the frequency dependent robustness margin is proposed and its properties are discussed. Implication of this regularization in the case of polynomial families with affine dependency on the uncertainty is pointed out.en-USrobust controllinear systemsIntelligent ServomechanismsTechnical Report