The value of tmnxSysRollbackSave specifies whether to save the existing configuration in a rollback checkpoint file. When SET to the value of 'doAction' the system will save the configuration in a new rollback checkpoint file, with suffix '.rb'. Previously saved rollback files with the same name will increment the filename suffix by 1 up to a maximum of 9. For example, file.rb is moved to file.rb.1. The higher the number, the older the file is. An SNMP GET request on this object should return 'notApplicable'.