  We investigate the entanglement properties of pure quantum states describing
$n$ qubits. We characterize all multipartite states which can be maximally
entangled to local auxiliary systems using controlled operations. A state has
this property iff one can construct out of it an orthonormal basis by applying
independent local unitary operations. This implies that those states can be
used to encode locally the maximum amount of $n$ bits. Examples of these states
are the so--called stabilizer states, which are used for quantum error
correction and one--way quantum computing. We give a simple characterization of
these states and construct a complete set of commuting unitary observables
which characterize the state uniquely. Furthermore we show how these states can
be prepared and discuss their applications.
