An HR diagram showing the black body log L vs. log T_eff coordinates of the central stars of the PNe with spectra modelled by Cloudy (Table 8) and a selection of low mass H and He burning model tracks from Vassiliadis & Wood (1997). The points are coded (and coloured) for the three regions (F42, F56 and F34) as in Fig. 2. Representative error bars on temperature at higher and lower temperatures are shown; the error bars in log L were computed from the errors on dereddened absolute Hβ flux in Table 12.