Luminosity (k)-stretch (s) relationship from Cano (2014). Plotted also are the rest-frame s and k values of SN 2016jca in B (blue), V (green) and R (red). The best-fitting is shown in black, and the 1σ error region is shown in shaded grey. The best-fitting values for the fitted line are found in the main text. The k and s values in R are marginally consistent within 1σ, while those in B and V are entirely consistent with the relationship.