The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it is written from left to right. When changing direction it is not mirrored. The word that U+04D9 forms with similar adjacent characters prevents a line break inside it. The glyph can be confused with one other glyph.
The Wikipedia has the following information about this codepoint:
Schwa (Ә ә; italics: Ә ә) is a letter of the Cyrillic script, derived from the Latin letter schwa. It is currently used in Abkhaz, Bashkir, Dungan, Itelmen, Kalmyk, Kazakh, Khanty, Kurdish, Uyghur and Tatar. It was also used in Azeri, Karakalpak, and Turkmen before those languages switched to the Latin alphabet. The Azeri and some other Latin-derived alphabets contain a letter of identical appearance (Ə/ə).
Representations
System
Representation (click value to copy)
Nº
1241
UTF-8
D3 99
UTF-16
04 D9
UTF-32
00 00 04 D9
URL-Quoted
%D3%99
HTML hex reference
ә
Wrong windows-1252 Mojibake
Ó™
Encoding: GB18030 (hex bytes)
81 30 E0 35
Encoding: KZ1048 (hex bytes)
BC
Encoding: PTCP154 (hex bytes)
BA
LATEX
\cyrchar\cyrschwa
Adobe Glyph List
afii10846
Adobe Glyph List
schwacyrillic
RFC 5137
\u'04D9'
Bash and Zsh inside echo -e
\u04D9
C and C++
\u04D9
C#
\u04D9
CSS
\0004D9
Excel
=UNICHAR(1241)
Go
\u04D9
JavaScript
\u04D9
Modern JavaScript since ES6
\u{4d9}
JSON
\u04D9
Java
\u04D9
Lua
\u{4D9}
Matlab
char(1241)
Perl
"\x{4D9}"
PHP
\u{4d9}
PostgreSQL
U&'\04D9'
PowerShell
`u{4D9}
Python
\u04D9
Ruby
\u{4d9}
Rust
\u{4d9}
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