What ᠏ means
FVS4 tells Mongolian text software which letter form to show.
A proposal dated 23 January 2020 added it to computer text encoding for historical Mongolian spellings that needed extra letter forms, including dotted forms the earlier selectors could not cover. The proposal describes an encoding control, not a handwritten sign.
FVS1, FVS2, and FVS3 are earlier members of its selector family. The wider Mongolian encoding model also includes Hudum Mongolian and the related Todo, Manchu, and Sibe writing systems.
Why does FVS4 seem to disappear?
FVS4 itself has no visible form.
It must follow a supported Mongolian letter. When the pairing is supported, text-shaping software—the part that chooses how letters appear—may show a different form of the letter. An isolated selector or unsupported pairing can be ignored. The visible result depends on the font and its Mongolian shaping support.
How do I type FVS4?
Put it immediately after the Mongolian letter it modifies.
The exact key sequence depends on the keyboard or input method you use.
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 ᠏
᠏\180FCodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.