This character is a Other Symbol and is commonly used, that is, in no specific script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. The word that U+2403 forms with similar adjacent characters prevents a line break inside it.
The Wikipedia has the following information about this codepoint:
The End-of-Text character (ETX) is a control character used to inform the receiving computer that the end of a record has been reached. This may or may not be an indication that all of the data in a record have been received. It is often used in conjunction with Start of Text (STX) and Data Link Escape (DLE), e.g., to distinguish data frames in the data link layer. All this use is pretty much obsolete.
In both ASCII and EBCDIC, ETX is code point 0x03, often displayed as ^C, and a (ASCII) terminal can send it by typing Ctrl+C.
Control-C is often used to interrupt a program or process, a standard that started with Dec operating systems. In TOPS-20, it was used to gain the system's attention before logging in. mIRC uses ETX as the escape character to start a command to set the color.
Representations
System
Representation (click value to copy)
Nº
9219
UTF-8
E2 90 83
UTF-16
24 03
UTF-32
00 00 24 03
URL-Quoted
%E2%90%83
HTML hex reference
␃
Wrong windows-1252 Mojibake
âƒ
Encoding: GB18030 (hex bytes)
81 37 83 33
RFC 5137
\u'2403'
Bash and Zsh inside echo -e
\u2403
C and C++
\u2403
C#
\u2403
CSS
\002403
Excel
=UNICHAR(9219)
Go
\u2403
JavaScript
\u2403
Modern JavaScript since ES6
\u{2403}
JSON
\u2403
Java
\u2403
Lua
\u{2403}
Matlab
char(9219)
Perl
"\x{2403}"
PHP
\u{2403}
PostgreSQL
U&'\2403'
PowerShell
`u{2403}
Python
\u2403
Ruby
\u{2403}
Rust
\u{2403}
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