What ⦗ means
It opens a bracketed expression in mathematical notation.
The Unicode proposal for this mathematical bracket set drew symbols from the STIX collection and the ISO TECH entity set, a collection of named symbols for technical documents.
This is the narrow mathematical form. Wider tortoise-shell marks are CJK (Chinese, Japanese, and Korean) punctuation; they belong to text layout, while this one is intended for mathematics.
Don't confuse it with
4Questions people ask
1Why does ⦗ show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type ⦗
Windows (Word)
Alt+XType 2997, then Alt+X to get ⦗.
Windows
Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win + .).
macOS
Control+Command+SpaceOpen the character viewer and search “left black tortoise shell bracket”.
Linux
Ctrl+Shift+UType 2997, then Enter or Space.
HTML
⦗CSS
\2997Codes and encoding1 code points
HTML decimal
⦗
HTML hex
⦗
CSS content
content: "\2997";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%A6%97
1
On screen
1
Code points
1
JS .length
3
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.