What ⤖ means
⤖ is the arrow for a bijection between two sets. A bijection pairs every item on each side with exactly one item on the other: no two inputs share an output, and nothing on the other side is left unmatched.
Z notation is a formal system for expressing mathematical specifications; there, ⤖ marks this kind of mapping.
Is ⤖ the same as ↠ or ↣?
No; ⤖ combines onto and one-to-one mapping. In common set-mapping notation, ↠ marks a map that reaches every item in the target set, while ↣ marks one where different inputs cannot share an output. ⤖ signals both properties.
On 2026-09-05, fonts could draw ⤖ differently, and a font without the glyph could show a replacement box.
Specialist mathematical notation: it marks a formal mapping, not a general directional cue.
Use it only when your formula defines what the two heads and tail mean.
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 ⤖
⤖\2916Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.