What ⚇ means
The 2016 proposal shows them in research, not game notation.
The proposal lists ⚆, ⚇, ⚈ and ⚉ as Go markers and reproduces the set in mathematical work about the game; it says they do not seem to be attested in actual Go notation. In printed commentary, a triangle marks the stone or group under discussion. A square distinguishes another one when the same diagram already contains a triangle.
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 2687, 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 “white circle with two dots”.
Linux
Ctrl+Shift+UType 2687, then Enter or Space.
HTML
⚇CSS
\2687Codes and encoding1 code points
HTML decimal
⚇
HTML hex
⚇
CSS content
content: "\2687";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%9A%87
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.