  A universal C*-algebra of gauge invariant operators is presented, describing
the electromagnetic field as well as operations creating pairs of static
electric charges having opposite signs. Making use of Gauss' law, it is shown
that the string-localized operators, which necessarily connect the charges,
induce outer automorphisms of the algebra of the electromagnetic field. Thus
they carry additional degrees of freedom which cannot be created by the field.
It reveals the fact that gauge invariant operators encode information about the
presence of non-observable gauge fields underlying the theory. Using the
Gupta-Bleuler formalism, concrete implementations of the outer automorphisms by
exponential functions of the gauge fields are presented. These fields also
appear in unitary operators inducing the time translations in the resulting
representations of the universal algebra.
