End of Transmission Block

The End of Transmission Block symbol was used in computer terminals, printers, text processing systems, and telecommunication equipment to indicate the end of a block of data being transmitted.

Its function was to divide transmitted data into blocks, allowing receiving devices to determine the boundaries of data blocks and properly process the received information. This was especially useful when data was transmitted in synchronous mode, and devices needed to have the information about when the current block of data ended and the next one began.

As for modern computer systems and applications, the U+0017 symbol is rarely used there, since other mechanisms and protocols are employed to separate and process data blocks.

Like many other control symbols, this one has no visible representation and doesn't occupy a lot of space on screen or in typed text. However, there is a separate symbol in Control Pictures2400–243F representing the graphical image of End of Transmission Block as the abbreviation ETB (End of Transmission Block) — ␗.

The symbol “End of Transmission Block” is included in the “C0 controls” subblock of the “Basic Latin” block and was approved as part of Unicode version 1.1 in 1993.