Colour–colour plots for different regions across the source. The dash-dotted red line indicates the locus of points for a power-law spectrum. Left: the dashed green line and the solid black line (overlapping) represent the locus of points taken by KGJP and JP models, respectively, with an injection index of α₀ = −1.5. The dash-dotted blue line represents a CIJP model with the same injection index. The dash-dotted black line represents a KGJP model with injection index of α₀ = −1. Right: the dashed green line and the dashed black line (overlapping) represent the locus of points taken by KGJP and JP models, respectively, with injection index of α₀ = −0.6. The dash-dotted blue line represents a CIJP model with the same injection index. Marker sizes are proportional to the low-frequency spectral indices for a given region and marker colours are proportional to the high-frequency spectral indices. Numbers label the regions.