In a node environment save files can be created in multiplex operation. If one of the last backups which was used as input during offline copying was created in multiplex operation, the newly created save file must also be created entirely in multiplex operation. This means that all input save versions which were not created in multiplex operation but were used during offline copying must also be multiplexed in the new output save file so that the complete structure of the new save file remains consistent. Thus if a full backup is performed with FROM=*LATEST-BACKUPS-OR-S0 and at least one save version is multiplexed in the HSMS archive in question, the backup of S0 (in other words the modified files) is also created in multiplex operation, even if the user did not request this. The multiplex factor in this case is 1.