  Let G/H be a unimodular real spherical space which is either absolutely
spherical or wave-front. It is shown that every tempered representation of G/H
embeds into a relative discrete series of a boundary degeneration of G/H. If in
addition G/H is of wave-front type it follows that the tempered representation
is parabolically induced from a discrete series representation of a lower
dimensional real spherical space. Final version. To appear in Acta Math.
