  We investigate under which conditions cold, fan-shaped winds can be steadily
launched from thin (Keplerian) accretion discs. Such winds are
magneto-centrifugal winds launched from a thin annulus in the disc, along open
magnetic field lines that fan out above the disc. In principle, such winds
could be found in two situations: (1) at the interface between an inner Jet
Emitting Disc, which is itself powering magneto-centrifugally driven winds, and
an outer standard accretion disc; (2) at the interface between an inner closed
stellar magnetosphere and the outer standard accretion disc. We refer to
Terminal or T-winds to the former kind and to Magnetospheric or M-winds to the
latter.
  The full set of resistive and viscous steady state MHD equations are analyzed
for the disc (the annulus), which allow us to derive general expressions valid
for both configurations. We find that, under the framework of our analysis, the
only source of energy able to power any kind of fan-shaped winds is the viscous
transport of rotational energy coming below the inner radii. Using standard
local $\alpha$ prescriptions for the anomalous (turbulent) transport of angular
momentum and magnetic fields in the disc, we derive the strength of the
transport coefficients that are needed to steadily sustain the global
configuration. It turns out that, in order for these winds to be dynamically
relevant and explain observed jets, the disc coefficients must be far much
larger than values expected from current knowledge of turbulence occurring
inside proto-stellar discs.
  Either the current view on MHD turbulence must be deeply reconsidered or
steady-state fan-shaped winds are never realized in Nature. The latter
hypothesis seems to be consistent with current numerical simulations.
