You cannot use a command to generate or transform flat file data and send the output to the flat file source at run time.

You cannot use an indirect source type.

You cannot append output data to target files and reject files. The Data Integration Service truncates the target files and reject files before writing the data.

You cannot use the command output type.

When the flat file target is in a partitioned mapping, you cannot write to a merge file that contains the target output for all partitions. The Data Integration Service concurrently writes the target output to a separate file for each partition.