Area below the Δ_X′ cumulative curve, A, (left) and median Δ_X′ value as a function of cluster age for LMC (red dots) and SMC (aqua dots) clusters with the eMSTO. Open and filled triangles are inferred from simulated CMDs of nonrotating stellar populations with different ages derived from the Padova and Geneva database, respectively. The diamonds correspond to coeval stellar populations with different rotation rates from the Geneva database. See text for details.