A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.