  We consider "unphysical", kinematic observables that do not commute with the
constraints of a gauge system in the context of an extension of the system. We
show that these observables, while not predictable, can nevertheless be said to
have a physical interpretation. They implement Rovelli's concept of partial and
relational observables. We investigate the propositional structure of these
observables and point out interpretational issues. We find that to make
relational statements in the quantum theory one must deal directly with these
observables. In particular we argue that in this scenario the spectra of
kinematic observables are what is experimentally accessible.
