This character string will be used to determine which file is downloaded to the NIs to be brought up by the chassis manager. Only files with suffixes (the part of the file name following '.') matching this character string will be downloaded to NIs which are inserted into the chassis or reset. If the chassis is rebooted these files will be used for the initial NI loads. This value can only be set on the Primary MPM. If automatic synchronization is enabled and the required image files on the Secondary match those on the Primary (State is Redundant or CONFIG FB) then the value set will be copied to the Secondary after the first 5min period of no configuration updates or when a configsync is envoked.