  The internal structure of a charged spherical black hole is still a topic of
debate. In a nonrotating but aspherical gravitational collapse to form a
spherical charged black hole, the backscattered gravitational wave tails enter
the black hole and are blueshifted at the Cauchy horizon. This has a
catastrophic effect if combined with an outflux crossing the Cauchy horizon: a
singularity develops at the Cauchy horizon and the effective mass inflates.
Recently a numerical study of a massless scalar field in the \RN background
suggested that a spacelike singularity may form before the Cauchy horizon
forms. We will show that there exists an approximate analytic solution of the
scalar field equations which allows the mass inflation singularity at the
Cauchy horizon to exist. In particular, we see no evidence that the Cauchy
horizon is preceded by a spacelike singularity.
