Tools in this 4D (x-y-v-Intensity) Space
Speedometers: v(z) gives gas velocity
Tachometers: v(z)[(x,y)] measures angular momentum
Thermometers: line strength inter-comparisons give Tkinetic, Tex (and t)
Pseudo-thermometers: line widths give velocity dispersion (usually >> sound speed)
Magnetometers: Zeeman Effect & polarized spectral-lines give B
Combinations give density, mass