What ⎳ means
It provides the lower piece of a large sum sign.
In mathematical typesetting, separate font pieces let a tall operator keep a stroke weight that matches nearby symbols. ⎲ is the top and ⎳ the bottom in the two-row construction for ∑.
Their design originated in older font standards. Unicode preserves them as compatibility characters for display or print data; stored mathematical text should use the ordinary ∑ operator, not these pieces.
What it means when someone sends it to you
2 readings⎲ followed by ⎳ in layout data
A typesetting system can assemble a two-row, oversized ∑.
⎳ alone in plain text
Only the lower fragment appears; no complete summation operator is present.
Don't confuse it with
1Questions 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 23B3, 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 “summation bottom”.
Linux
Ctrl+Shift+UType 23b3, then Enter or Space.
HTML
⎳CSS
\23B3Codes and encoding1 code points
HTML decimal
⎳
HTML hex
⎳
CSS content
content: "\23B3";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%8E%B3
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.