The available data on the forward charge exchange of nucleons on the deuteron up to 2 GeV per nucleon are reviewed. The value of the inclusive nd → pnn/np → pn cross section ratio is sensitive to the fraction of spinindependent neutron-proton backward scattering. The measurements of the polarisation transfer in d( n, p ){nn} or the deuteron analysing power in p( d, {pp})n in high resolution experiments, where the final nn or pp pair emerge at low excitation energy, depend upon the longitudinal and transverse spin-spin np amplitudes. The relation between these types of experiments is discussed and the results compared with predictions of the impulse approximation model in order to see what new constraints they can bring to the neutron-proton database.