ASCII 21

Negative Acknowledge (NAK)

Control character

Used in some binary protocols to indicate a failed transmission.

All encodings at a glance

JavaScript

String.fromCharCode(21); // "NAK"
21.toString(16); // "15"

Python

chr(21)           # control char NAK
ord(chr(21))      # 21
hex(21)           # '0x15'

HTML

&#21;   <!-- numeric entity (no named entity for this character) -->

18 — DC2

Device Control 2

19 — DC3

Device Control 3 (XOFF)

20 — DC4

Device Control 4

22 — SYN

Synchronous Idle

23 — ETB

End of Transmission Block

24 — CAN

Cancel