  The full set of equations governing the structure and the evolution of
self--gravitating cylindrically symmetric dissipative fluids with anisotropic
stresses, is written down in terms of scalar quantities obtained from the
orthogonal splitting of the Riemann tensor (structure scalars), in the context
of general relativity. These scalars which have been shown previously (in the
spherically symmetric case) to be related to fundamental properties of the
fluid distribution, such as: energy density, energy density inhomogeneity,
local anisotropy of pressure, dissipative flux, active gravitational mass etc,
are shown here to play also a very important role in the dynamics of
cylindrically symmetric fluids. It is also shown that in the static case, all
possible solutions to Einstein equations may be expressed explicitly through
three of these scalars.
