This character is a Nonspacing Mark and is mainly used in the Cham script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Nonspacing Mark. When changing direction it is not mirrored. U+AA31 prohibits a line break before it.
The Wikipedia has the following information about this codepoint:
The Cham script (Cham: ꨀꨇꩉ ꨌꩌ)is a Brahmic abugida used to write Cham, an Austronesian language spoken by some 245,000 Chams in Vietnam and Cambodia. It is written horizontally left to right, just like other Brahmic abugidas.
Representations
System
Representation (click value to copy)
Nº
43569
UTF-8
EA A8 B1
UTF-16
AA 31
UTF-32
00 00 AA 31
URL-Quoted
%EA%A8%B1
HTML hex reference
ꨱ
Wrong windows-1252 Mojibake
◌ꨱ
Encoding: GB18030 (hex bytes)
82 37 A1 32
RFC 5137
\u'AA31'
Bash and Zsh inside echo -e
\uAA31
C and C++
\uAA31
C#
\uAA31
CSS
\00AA31
Excel
=UNICHAR(43569)
Go
\uAA31
JavaScript
\uAA31
Modern JavaScript since ES6
\u{aa31}
JSON
\uAA31
Java
\uAA31
Lua
\u{AA31}
Matlab
char(43569)
Perl
"\x{AA31}"
PHP
\u{aa31}
PostgreSQL
U&'\AA31'
PowerShell
`u{AA31}
Python
\uAA31
Ruby
\u{aa31}
Rust
\u{aa31}
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