Measurements from our joint strong lensing and stellar dynamical models, without any kinematic data (grey) and with mock IFU stellar kinematics (orange and blue). The corner plot shows the most relevant parameters in the fit, consisting of the lens distance, D_d, int, time-delay distance, D_Δt, int, internal mass-sheet parameter, λ_int, and orbital anisotropy, β_z. The contours highlight the 1σ, 2σ, and 3σ confidence regions. The black points (lines) depict the mock input values. Without any kinematics, D_Δt, int and λ_int are highly degenerate, while D_d, int and β_z are unconstrained. The posterior PDFs for D_d, int and β_z are virtually flat in this case, which is why we only show the 2D contours in the D_Δt, int–λ_int space. IFU data will considerably tighten the constraints. In the IDEAL case, the mock input values are recovered within 2σ. In the FIDUCIAL case, the mock input values are also recovered within the 2σ bands, but with larger relative uncertainties for the lens distance (δD_d, int/D_d, int ≈ 4%). These measurements are independent of cosmological model assumptions.