Discrete gauge fields

The use of proper time as a tool for causality implementation in field theory is clarified and extended to allow a manifestly covariant definition of discrete fields proper to be applied in field theory and quantum mechanics. It implies on a constraint between a radiation field and its sources, valid in principle for all fundamental interactions and with a solid experimental confirmation for the electromagnetic one. Some results of its applications to an abelian classical theory (electrodynamics taken as a first example), and with the discrete field being regarded as a classical representation of the field quantum (photon) are anticipated in order to illuminate the physical meaning and the origins of gauge fields and of their symmetries and singularities. They are associated to a loss of field-source coherence.