  A framework for the interpretation of the spectral states of black hole X-ray
transients based on the diversity of accretion disk models is introduced.
Depending on the mass accretion rate, it is proposed that the accretion disk is
described by one or a combination of the following structures: optically thick
disk, advection-dominated disk, corona-disk, and non-steady state disk. In
particular, it is suggested that the very high, high, low, and off states are
characterized by mass accretion rates of decreasing magnitude. The very high
state corresponds to mass accretion rates near the Eddington limit in which an
optically thin non steady inner region is surrounded by an optically thick
structure. In the high state, the inner region is optically thin and
advection-dominated or optically thick. The low hard state is interpreted in
terms of a disk-corona system and the off state in terms of an optically thin
disk dominated by advective energy transport into the black hole. The possible
observational consequences of such a paradigm are discussed.
