What ⟧ means
It closes a paired mathematical or semantic delimiter.
In Z notation, ⟦...⟧ encloses a bag display. In formal semantics, the pair can mark an expression's denotation: the value or interpretation assigned to it. The same bracket shape has no single meaning outside its notation.
Unlike the wide East Asian closing bracket 〛, ⟧ is a narrow mathematical form; the two are not interchangeable in technical text.
Why do semantics papers use ⟦ ⟧?
The pair can mark the value an expression denotes.
The double-bracket convention developed from work on truth values and interpretation. In the mid-1960s, Dana Scott described replacing bar-style marks with readable double brackets as formulas grew longer. In the late 1960s, the notation entered programming-language semantics, then natural-language semantics.
That history explains the register: ⟦expression⟧ tells a specialist reader to interpret the expression under a particular framework; the framework supplies the exact rules.
Specialist mathematical and semantic notation; use it when the surrounding work defines that bracket convention.
Alone, ⟧ leaves the convention unclear; look for its matching ⟦ and the surrounding notation.
What it means when someone sends it to you
3 readingsDon't confuse it with
2Combination ideas
2Questions 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 ⟧
⟧\27E7Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.