0-9 | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A transmission control character used as a request for a response from the station with which a connection has been set up. Note: The response may include station identification, the type of equipment in service, and the status of the remote station.