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+25D9 forms with similar adjacent characters prevents a line break inside it.
The CLDR project calls this character “filled square containing hollow circle” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: circle, containing, filled, hollow, inverse, square.
The Wikipedia has the following information about this codepoint:
Geometric Shapes is a Unicode block of 96 symbols at code point range U+25A0–25FF.
Representations
System
Representation (click value to copy)
Nº
9689
UTF-8
E2 97 99
UTF-16
25 D9
UTF-32
00 00 25 D9
URL-Quoted
%E2%97%99
HTML hex reference
◙
Wrong windows-1252 Mojibake
â—™
Encoding: GB18030 (hex bytes)
81 37 9F 32
Adobe Glyph List
invcircle
Adobe Glyph List
whitecircleinverse
digraph
Ic
RFC 5137
\u'25D9'
Bash and Zsh inside echo -e
\u25D9
C and C++
\u25D9
C#
\u25D9
CSS
\0025D9
Excel
=UNICHAR(9689)
Go
\u25D9
JavaScript
\u25D9
Modern JavaScript since ES6
\u{25d9}
JSON
\u25D9
Java
\u25D9
Lua
\u{25D9}
Matlab
char(9689)
Perl
"\x{25D9}"
PHP
\u{25d9}
PostgreSQL
U&'\25D9'
PowerShell
`u{25D9}
Python
\u25D9
Ruby
\u{25d9}
Rust
\u{25d9}
Click the star button next to each label to set this representation as favorite or remove it from the favorites. Favorites will be shown initially. (Favorites are stored locally on your computer and never sent over the internet.)