11 Facts About Control character

In computing and telecommunication, a control character or non-printing character is a code point in a character set, that does not represent a written symbol.

The NULL Control character is represented by Ctrl-@, "@" being the code immediately before "A" in the ASCII Control character set.

The carriage return Control character, when sent to such a device, causes it to put the Control character at the edge of the paper at which writing begins.

The concept of a control character had always been somewhat limiting, and was extremely so when used with new, much more flexible, hardware.

The start of text Control character marked the end of the header, and the start of the textual part of a stream.

The end of transmission block Control character was used to indicate the end of a block of data, where data was divided into such blocks for transmission purposes.

The negative acknowledge Control character is a definite flag for, usually, noting that reception was a problem, and, often, that the current element should be sent again.

The acknowledge Control character is normally used as a flag to indicate no problem detected with current element.

The enquire Control character is generally used by a master station to ask a slave station to send its next message.

Data link escape character was intended to be a signal to the other end of a data link that the following character is a control character such as STX or ETX.

Since the position of a NUL Control character has no holes punched, it can be replaced with any other Control character at a later time, so it was typically used to reserve space, either for correcting errors or for inserting information that would be available at a later time or in another place.