Zero-width and invisible
HANGUL FILLER (U+3164)
A Hangul compatibility character with no shape, used historically to fill an empty slot in a Korean syllable block.
- Codepoint
U+3164- Category
- Zero-width and invisible
- Removed by default
- Yes
- Governing option
- No option needed
- Can be load-bearing
- No
Where it comes from
Legacy Korean encodings, and from gaming and social platforms where it is the classic way to make an empty username or a blank message.
Why it matters
It is a letter as far as Unicode is concerned, so it passes validators that reject whitespace and control characters, and it renders as nothing. That combination is why it turns up in usernames and in payloads.
Before and after
A "letter" with no glyph, sitting in the middle of a name.
The character is shown as a labelled chip so you can see where it sits. In your text it draws nothing at all.
When it is legitimate
Round-tripping older Korean data that used it as a placeholder. Modern Korean text does not need it.
How to remove it
The default pass removes it, together with U+FFA0 HALFWIDTH HANGUL FILLER, which behaves the same way.
Is it an AI watermark?
Not a watermark
No. Its fame comes from blank usernames, not from generated text. Seeing one says something about the platform the text passed through.
No connection to machine-generated text. It comes from software, from a keyboard, or from a person.
Questions
Why are blank usernames made of it?
Because most username validators require letters and reject spaces. A Hangul filler is a letter that draws nothing, so it satisfies the rule and displays as empty.
Is it part of normal Korean?
No. Modern Korean text does not use it; it exists for compatibility with older encodings.
Check your own text
Paste anything into the cleaner to see every hidden character it contains, with position, codepoint and what happens to each one. Nothing is uploaded.