Charge radius are used to determine the recommended values. The 2014 CODATA recommended values are: Recent measurement of the Lamb shift in muonic hydrogen (an exotic atom consisting of a proton and a negative muon) indicates a significantly lower value for the proton charge radius, : the reason for this discrepancy is not clear. Charge radius The rms charge radius is a measure of the size of an atomic nucleus, particularly of a proton or a deuteron. It can be measured by the scattering of electrons by the nucleus and also inferred from the effects of finite nuclear size on electron energy
Unique Particle Attribution which disambiguates it by saying that when an element matches both an element particle and a wildcard, the element particle wins. However, the UPA constraint itself remains in version 1.1. Unique Particle Attribution The Unique Particle Attribution (UPA) rule is a mechanism to prevent ambiguity in W3C XML Schema version 1.0. Due to the UPA rule the XML schema fragment given below is prohibited: Given the XML instance fragment: it is ambiguous whether <x> should be associated with the element declaration (xsd:element name="x"), or the wildcard (xsd:any). This ambiguity violates the UPA rule and the corresponding XML schema therefore needs