  We revisit the stability issue of determining the conductivity at the
boundary from the corresponding Dirichlet-to-Neumann map. We discuss both the
method based on singular solutions and the one built on the localized
oscillating solutions. Our primary objective is not establishing new results on
this subject even if the present work contains some new ones. We mainly clarify
some points in the existing proofs and make some comments. We also derive some
consequences of the stability inequality of the determination of the
conductivity at the boundary from the Dirichlet-to-Neumann map.
