  Master character of the multidimensional homogeneous Euler equation is
discussed. It is shown that under restrictions to the lower dimensions certain
subclasses of its solutions provide us with the solutions of various
hydrodynamic type equations. Integrable one dimensional systems in terms of
Riemann invariants and its extensions, multidimensional equations describing
isoenthalpic and polytropic motions and shallow water type equations are among
them.
