Three-dimensional distribution of the U Her merged maser spatial components and their associated velocities according to the outflow velocity law given by Eq. (2). The distribution is seen from three cardinal directions: on the sky (a), ‘from the side’ (b) and ‘from above’ (c). In (b) and (c) the observer is to the left. The maser components are represented by filled circles with colours according to their V_los (see scale at bottom). Their diameters are proportional to the logarithm of their flux density. The central star is symbolised by a black circle at (0,0).