Where each parameter label sits on its method's ramp
Source:R/plots_utils.R
method_parameter_positions.RdAnchored on the range the configuration declares rather than on the values one figure happens to show. A figure plotting w in 0.1, 0.5, 0.9 and one plotting all nine weights put w = 0.5 at the same place, and so give it the same shade; ranking the values present would not.
Labels carrying no recoverable number - categorical parameters - fall back to sorted order, which is at least reproducible between runs.