2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/150922This paper gives a representation of the most general positive operator valued measure in Minkowski space-time, covariant with respect to the Poincare' group. It provides the correct mathematical description of the space-time coordinates of a quantum event, described by a quantum object with suitable properties. It is known that these coordinates cannot be represented by self-adjoint operators or by the corresponding projection valued measure.21 pages, LATEX, no figures. This revised version contains several more important references and a short section on non-normalized positive operator valued measuresQuantum Physicstext