Examples of fits of the integrated intensities of our three transitions of SiO. On the y-axis is the integrated intensity (K km s^-1), and on the x-axis is the rotational quantum number of the upper level of the transition. The observations are the black squares linked by the thick black lines, on all three panels. The 3σ errorbars are shown in the figure. The model results are displayed in colour (blue and red), with the indication of the specific shock parameters on each panel. a) C-type shock models: best fit shock parameters n_H = 10⁴ cm^-3, no SiO initially in the grain mantles; b) CJ-type shock models: best fit shock parameters n_H = 10⁴ cm^-3 and v_s = 28 km s^-1, with 1% of elemental silicon initially in the grain mantles, as SiO; c) CJ-type shock models: best fit shock parameters n_H = 10⁴ cm^-3 and v_s = 30 km s^-1, with 10% of the silicon initially in the grain mantles as SiO.