transmission control (TC)
Transmission control(TC) characters are used exclusively for control purposes in character-oriented control procedures. They control the operation between two or more data stations.
The ten transmission control characters, marked TC1 to TC10, include TC1 is Start of Heading( SOH), TC2 Start of Text( STX), End of Text( ETX), End of Transmission ( EOT), Enquiry( ENQ), Acknowledgment ( ACK), Data Link Escape ( DLE), Negative Acknowledgement ( NAK),Synchronization( SYN) and End of Transmission Block ( ETB).