Histogram of the measurements of the EWs of the 500 random stacks from bootstrapping for the MgII 2793 and 2803 Å lines stacked at random redshifts from the cluster redshift distribution. We mark with a vertical solid line the position of our measurement of EW₂₇₉₆ corresponding to 0.056 ± 0.015 Å, and with a vertical dashed line the mean of EW₂₇₉₆ of 0.003 Å. We measure a standard deviation from the distribution of EW₂₇₉₆ of 0.015 Å, which, considering our tentative detection, gives us a significance of 3.7σ.