Backing Up SE - Questions

The INFORMIX-SE Administration manual states Chapter 8-190 Periodically, you should Create a backup of your database. Agree Initiate a new transaction log file Agree Archive your transaction log file on tapes. Why? The first chapter states "In general, every transaction log file must have a corresponding archive copy of the database." What does in general mean followed by a must? Anyone? I don't see why the transaction log needs to be backed up as long as it is the one started after the most recent database backup. Examples. Perform Backup ============== Stop all users accessing database Backup database .dat and idx files. Empty log file (no need to be backed up?) Start log file Let users back in. If the database disk falls over. =============================== Restore backed up data. Rollforward log file (assuming on different disk) The notes suggest that Chapter 9-190 Para. 1. If the log file is getting too big for the disk then ==================================================== Backup log file Initiate another log file Backup the database Back to my question. Why backup the log file at all? If we have the database backed up we can empty the logfile, start a new one and roll it forward if we need to. Comments?