The following sections describe the performance of the X31 beam line under the operating conditions offered by the DORIS III storage ring. The experiments carried out for this purpose were performed at different times throughout the two year period between November '91 and November '93 during which time the characteristics of the storage ring itself were periodically changing due to the rebuilding and insertion of several new experiments in one quadrant of the ring during the first-half of this period and then due to the decision that the ring was to become a fully dedicated synchrotron source in May '93.