Super-allowed Fermi beta-decay is analyzed in order to determine the u - d element of the Cabibbo-Kobayashi-Maskawa matrix; combining this with particle data yields: |Vud|^2 + |VUs|^2 + |Vub|^2 = 1.0001 f0.0017. Alternatively, the assumption of unitarity for the CKM matrix yields: 1/2Q = 2.9 ± 0.5 where Q is the mean charge of the fermionic fields between which the bata-decay of the nucleon takes place.