def _get_crmod_abmn(self):
        """return a Nx2 array with the measurement configurations formatted
        CRTomo style
        """
        ABMN = np.vstack((
            self.configs[:, 0] * 1e4 + self.configs[:, 1],
            self.configs[:, 2] * 1e4 + self.configs[:, 3],
        )).T.astype(int)
        return ABMN
return a Nx2 array with the measurement configurations formatted
        CRTomo style