  We discuss possibilities to test physics beyond the Standard Model in
$\vert\Delta c\vert=\vert\Delta u\vert= 1$ semileptonic, hadronic and missing
energy decay modes. Clean null test observables such as angular observables,
CP-asymmetries and lepton universality tests are presented and
model-independent correlations as well as details within flavorful,
anomaly-free $Z^\prime$ models are worked out.
