  In the perturbative field-theoretical models we investigate the inclusion of
the electromagnetic interactions into the purely strong theory that describes
hadronic processes. In particular, we study the convention for splitting
electromagnetic and strong interactions and the ambiguity of such a splitting.
The issue of the interpretation of the parameters of the low-energy effective
field theory in the presence of electromagnetic interactions is addressed, as
well as the scale and gauge dependence of the effective theory couplings. We
hope, that the results of these studies are relevant for the electromagnetic
sector of ChPT.
