This character is a Connector Punctuation and is commonly used, that is, in no specific script. The character is also known as Greek enotikon.
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+203F forms with similar adjacent characters prevents a line break inside it.
The Wikipedia has the following information about this codepoint:
The tie is a symbol in the shape of an arc similar to a large breve, used in Greek, phonetic alphabets, and Z notation. It can be used between two characters with spacing as punctuation, non-spacing as a diacritic, or (underneath) as a proofreading mark. It can be above or below, and reversed. Its forms are called tie, double breve, enotikon or papyrological hyphen, ligature tie, and undertie.
Representations
System
Representation (click value to copy)
Nº
8255
UTF-8
E2 80 BF
UTF-16
20 3F
UTF-32
00 00 20 3F
URL-Quoted
%E2%80%BF
HTML hex reference
‿
Wrong windows-1252 Mojibake
‿
alias
Greek enotikon
Encoding: EUC_JIS_2004 (hex bytes)
AB D8
Encoding: EUC_JISX0213 (hex bytes)
AB D8
Encoding: GB18030 (hex bytes)
81 36 A8 33
Encoding: ISO2022_JP_2004 (hex bytes)
1B 24 28 51 2B 58 1B 28 42
Encoding: ISO2022_JP_3 (hex bytes)
1B 24 28 4F 2B 58 1B 28 42
Encoding: SHIFT_JIS_2004 (hex bytes)
86 77
Encoding: SHIFT_JISX0213 (hex bytes)
86 77
AGL: Latin-5
uni203F
RFC 5137
\u'203F'
Bash and Zsh inside echo -e
\u203F
C and C++
\u203F
C#
\u203F
CSS
\00203F
Excel
=UNICHAR(8255)
Go
\u203F
JavaScript
\u203F
Modern JavaScript since ES6
\u{203f}
JSON
\u203F
Java
\u203F
Lua
\u{203F}
Matlab
char(8255)
Perl
"\x{203F}"
PHP
\u{203f}
PostgreSQL
U&'\203F'
PowerShell
`u{203F}
Python
\u203F
Ruby
\u{203f}
Rust
\u{203f}
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