Variation of the CSO radio power vs. the hotspot separation velocity. As a group, the sources with higher v _HS generally have a higher radio power P _rad and also a higher source power P _src. Individual sources are predicted to evolve from high- v _HS and low- P _rad to low- v _HS and high- P _rad with time as P _rad∝ v ⁻¹ _HS. Symbols indicate high-power (circles) and low-power (squares) CSOs. Arrows on the symbols indicate upper limits.