Various lines of the nebula (logarithmic representation). The different spectral regions originate from different spectra (ESO and SAAO) and thus vary in S/N ratio at similar physical intensities. The panels show the excitation groups (criteria see text). The high-excitation species (upper panel) concentrate at the central region. The medium-excitation species (middle panel) smoothly follow the total brightness and the radial behavior of the VLA image throughout the nebula. The low-excitation species (lower panel) are dominated by clumpy structures. The O ii λ3729 is at the edge of the CCD and its flux calibration is very uncertain. It is added only for comparison of the profiles.