[en] In the work a consistent approach is developed for to description of a scalar wave field generated by a system of point coherently emitting sources. In particular, the problem of the maxima and minima of the intensity of the superposition field under the conditions of Fraunhofer diffraction is discussed. The problem of determining the serial number of the wave field maxima is investigated. Generalization of the classical result related to interference, when an initial phase shift is present at two sources, is carried out