Summary of the virial parameter measurements α from Sect. 5. Blue symbols indicate data for structures of varying spatial size explored in this paper; see Sect. 2.2 for terminology and details. The blue cross with white filling indicates data for the Sgr D region that probably resides outside the CMZ, as studied here. Dark green bullets indicate the properties of reference Milky Way clouds that were explored in emission lines of N₂H⁺ and NH₃ tracing dense gas. Values for these are taken from the Kauffmann et al. (2013a) compilation. Light green diamonds denote CO-based data for the lower density gas in Milky Way clouds reported in the same compilation. The blue shaded area indicates the virial parameter that would hold for cloud fragments of radius 0.1 pc that have masses and velocity dispersions within the ranges indicated in the figure. Gray shading shows where α<α_cr ≈ 2, indicating the domain where nonmagnetized hydrostatic equilibria become unstable to collapse.