Relation between the retrieved heavy-element mass M_Z and planetary mass M, shown for the four main structures tested (CE, FM, DCA, and DCA3). Shown as dashed lines in a grey gradient are curves indicating the trends for fixed planetary compositions (0%, 50%, 90%, and 99% gas composition, respectively). Bayesian fits are shown using a power-law function M_Z = β M^α. A summary of the fitted parameters and correlation coefficients is presented in Tables 1 and 2.