Cumulative probability of the completeness-corrected PNLF is shown (in log scale for visual clarity) for the five different substructures and the two disc regions. This diagnostic plot illustrates in which magnitude ranges the PNLFs are most different. The region fainter than the limiting magnitude of the shallowest field (m₅₀₀₇ > 26.16 mag) is shown in grey. Here, we report the error bars depicting the photometric errors (multiplied by ten for visual clarity) with magnitudes in our survey, shown as black lines at m₅₀₀₇ = 20, 21, 22 and 23 mag respectively. The M^* fitted values for each of the PNLFs are robust in the entire survey area given the photometric accuracy (m_5007,err ∼ 0.014 mag at m₅₀₀₇ = 23 mag). Furthermore, the arrow in the upper left corner shows the mean photometric extinction within our survey area (A₅₀₀₇ = 0.21 mag).