Gain Notes for Revolution 400 JEM-X2: This is the first full revolution for JEM-X2 since its activation and warm-up revolution 399. The data now presented here (gain history, smoothing and Xe line) were obtained using the ISDC-generated gain history table produced with the CONS (consolidated) pipeline. This is the data that is archived in /isdc/arc/rev_2. It is the data that is delivered to observers. This data has a good gain history table which is smoothed well. All the science data from this revolution should be useable. WARNING: The data that was originally produced by the NRT pipeline was not useable. The gain history table was generated with antiquated software and was consequently filled almost entirely with null data. Use only the data from the archive. CAO 29/05/2006