CV WD masses from Ritter & Kolb (2003,V7.14) and Savoury et al. (2011), excluding systems with no published uncertainty in M_wd, and GK Per, for which only a lower limit M_wd ≥ 0.87  ±  0.24 M_⊙ has been determined. Systems shown as solid symbols are our “fiducial” sub-sample (Table 1). The dotted horizontal line indicates the division between C/O-core WDs (above) and He-core WDs (below), while the dotted vertical lines show the position of the orbital-period gap.