US
Unit Separator
ControlASCII 31 | Hex 0x1F | U+001F
US (code 31) separates individual data fields within a record. It is the finest-grained delimiter in ASCII's FS/GS/RS/US hierarchy, equivalent to a column separator in tabular data. Tab (HT, code 9) and comma often replace US in practice because they are printable and easier to type. US rarely appears in modern data formats, but some industrial and financial messaging protocols still use it internally where the delimiter must never appear in field values.
ASCII Code
Decimal
31
Hexadecimal
0x1F
Octal
37
Binary
0001 1111
Unicode
Code Point
U+001F
Escape
\u001f
UTF-8 Hex
0xE2 0x90 0x9F
UTF-8 Binary
111000101001000010011111
UTF-16
0x001F
UTF-32
0x0000001F
HTML Entities
Numeric

Hex

How to Type
HTML Entity

Unicode InputU+001F
Source Code Representations
C / Java
"\u001F"CSS
\001FJavaScript
"\u001F"Perl
\x{001F}Python 2
u"\u001F"Python 3
\u001FRuby
\u{001F}Frequently Asked Questions
What is ASCII code 31?
ASCII code 31 represents the Unit Separator character. In hexadecimal it is 0x1F, in binary 0001 1111, and in octal 37. This is a non-printable control character used for device signaling and data transmission control.
How do I type ASCII 31 on a keyboard?
Control characters are typically entered using Ctrl key combinations. For example, Ctrl+_ produces ASCII 31 in most terminal emulators. You can also use the HTML entity  in web pages.