  A modification of the saddle point method is proposed for computation of
non-stationary wave processes (pulses) in waveguides. The dispersion diagram of
the waveguide is continued analytically. A set of possible saddle points on the
dispersion diagram is introduced. A method of checking whether the particular
saddle points contribute terms to the field decomposition is proposed. A
classification of the waveguides based on the topology of the set of possible
saddle points is outlined.
