Line ratios comparing different ionization states of argon ([Ar II] 15.8 eV and [Ar III] 27.6 eV), sulfur ([S III] 23.3 eV and [S IV] 34.8 eV), and neon ([Ne II] 21.6 eV and [Ne III] 40.96 eV). Ratios are calculated for the Bar (maroon), Northern Arm (orange), and BC structures (yellow) in the spatial apertures labeled Region 1 (circles), Region 2 (squares), and Region 3 (triangles). The line of best fit and 1σ confidence band are shown in gray. Arrows indicate 3σ limits (due to either [Ne II] saturation or [S III] nondetection). The BC structures are more ionized than the Northern Arm, which is more ionized than the Bar; Regions 1 and 2 are always more ionized than Region 3.