Inelasticity and structure in pp → pp at medium energies

Above the inelastic threshold in pp scattering, the partial wave amplitudes get important inelastic contributions. This may lead to observable structure in pp spin measurements. One reviews some of the new pure spin total cross section data, and discuss the possible implications. It is suggested that a systematic study of the medium energy region might clarify some of the issues raised by the new data, in particular that of the existence of dibaryon resonances. Elastic and inelastic polarized pp measurements at ZGS energies are also reviewed as they may provide a clue about which medium energy measurements should be done