This character is a Math Symbol and is commonly used, that is, in no specific script.
The glyph is a small version of the glyph Glyph for U+003DEquals Sign. Its East Asian Width is wide. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. U+FE66 offers a line break opportunity at its position, except in some numeric contexts.
The Wikipedia has the following information about this codepoint:
The equals sign (British English) or equal sign (American English), also known as the equality sign, is the mathematical symbol =, which is used to indicate equality in some well-defined sense. In an equation, it is placed between two expressions that have the same value, or for which one studies the conditions under which they have the same value.
In Unicode and ASCII, it has the code point U+003D. It was invented in 1557 by Robert Recorde.
Representations
System
Representation (click value to copy)
Nº
65126
UTF-8
EF B9 A6
UTF-16
FE 66
UTF-32
00 00 FE 66
URL-Quoted
%EF%B9%A6
HTML hex reference
﹦
Wrong windows-1252 Mojibake
﹦
Encoding: BIG5 (hex bytes)
A1 E2
Encoding: BIG5HKSCS (hex bytes)
A1 E2
Encoding: CP950 (hex bytes)
A1 E2
Encoding: GBK (hex bytes)
A9 84
Encoding: GB18030 (hex bytes)
A9 84
Adobe Glyph List
equalsmall
RFC 5137
\u'FE66'
Bash and Zsh inside echo -e
\uFE66
C and C++
\uFE66
C#
\uFE66
CSS
\00FE66
Excel
=UNICHAR(65126)
Go
\uFE66
JavaScript
\uFE66
Modern JavaScript since ES6
\u{fe66}
JSON
\uFE66
Java
\uFE66
Lua
\u{FE66}
Matlab
char(65126)
Perl
"\x{FE66}"
PHP
\u{fe66}
PostgreSQL
U&'\FE66'
PowerShell
`u{FE66}
Python
\uFE66
Ruby
\u{fe66}
Rust
\u{fe66}
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