What ⧹ means
It hides selected variables without discarding their constraints. Z is a formal notation for describing software. A schema is a named bundle of variables and conditions. Hiding removes selected names from view, but the specification still requires some values for those variables to make its conditions true.
The 1992 Z Base Standard documents this use.
Don't confuse it with
2∖\
Set Minus
Unicode cross-references ∖ SET MINUS, the operator for removing one set's members from another. In Z notation, ⧹ specifically hides named parts of a schema.
Reverse Solidus
The ordinary backslash is a keyboard character used in file paths and programming. This mathematical symbol has a distinct Z-notation use.
Questions 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 29F9, 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 “big reverse solidus”.
Linux
Ctrl+Shift+UType 29f9, then Enter or Space.
HTML
⧹CSS
\29F9LaTeX
The `unicode-math` package maps `\xbsol` to ⧹.
Codes and encoding1 code points
HTML decimal
⧹
HTML hex
⧹
CSS content
content: "\29F9";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%A7%B9
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.