  It is known that nonadditive quantum codes are more optimal for error
correction when compared to stabilizer codes. The class of codeword stabilized
codes (CWS) provides tools to obtain new nonadditive quantum codes by reducing
the problem to finding nonlinear classical codes. In this work, we establish
some results on the kind of non-Pauli operators that can be used as decoding
observables for CWS codes and describe a procedure to obtain these observables.
