  The near threshold expansion of Feynman diagrams is derived from their
configuration space representation, by performing all x integrations. The
general scalar Feynman diagram is considered, with an arbitrary number of
external momenta, an arbitrary number of internal lines and an arbitrary number
of loops, in n dimensions and all masses may be different. The expansions are
considered both below and above threshold. Rules, giving real and imaginary
part, are derived. Unitarity of a sunset diagram with I internal lines is
checked in a direct way by showing that its imaginary part is equal to the
phase space integral of I particles.
