ETB
End of Transmission Block
ControlASCII 23 | Hex 0x17 | U+0017
ETB (code 23) marks the end of a transmission block without ending the full message. A large message can span multiple blocks, each terminated by ETB, with the final block terminated by ETX. This distinction allowed early serial protocols to implement per-block error checking on long transmissions. The receiver ACKs or NAKs each block individually, enabling retransmission of only corrupted blocks rather than the entire message.
ASCII Code
Decimal
23
Hexadecimal
0x17
Octal
27
Binary
0001 0111
Unicode
Code Point
U+0017
Escape
\u0017
UTF-8 Hex
0xE2 0x90 0x97
UTF-8 Binary
111000101001000010010111
UTF-16
0x0017
UTF-32
0x00000017
HTML Entities
Numeric

Hex

How to Type
HTML Entity

Unicode InputU+0017
Source Code Representations
C / Java
"\u0017"CSS
\0017JavaScript
"\u0017"Perl
\x{0017}Python 2
u"\u0017"Python 3
\u0017Ruby
\u{0017}Frequently Asked Questions
What is ASCII code 23?
ASCII code 23 represents the End of Transmission Block character. In hexadecimal it is 0x17, in binary 0001 0111, and in octal 27. This is a non-printable control character used for device signaling and data transmission control.
How do I type ASCII 23 on a keyboard?
Control characters are typically entered using Ctrl key combinations. For example, Ctrl+W produces ASCII 23 in most terminal emulators. You can also use the HTML entity  in web pages.