Use the DATA command to signal the start of a burst
of file content.
The DATA statement must come after a FILE command and preceed any EOF, ABORT, or QUIT commands. In most cases, a DATA statement must also come after a USER command so that the server on the receiving end will be able to direct the file content to an appropriate holding area or queue.
The syntax is
|is the number of bytes (octets) about to be sent
When the server receives a DATA command, it will then consume the next burst size bytes (the next burst size octets) as part of the file. After receiving exactly that many octets, it waits for another command from the client.