Zero-width and invisible
INVISIBLE SEPARATOR (U+2063)
The invisible comma, U+2063 INVISIBLE SEPARATOR: the separator between the indices in a subscript like aij.
- Codepoint
U+2063- Also written as
u2063\u2063⁣- Category
- Zero-width and invisible
- Removed by default
- Yes
- Governing option
- No option needed
- Can be load-bearing
- No
Copy and paste U+2063
To copy and paste INVISIBLE SEPARATOR (U+2063), press the button: the character itself goes to your clipboard, and Ctrl+V (Cmd+V on a Mac) pastes it anywhere you can type.
Where it comes from
Equation editors and MathML. In the wild it also shows up in text pasted out of scientific PDFs and from spreadsheet formula bars.
Why it matters
Another invisible codepoint that reads as nothing and compares as something. It is popular in zero-width steganography for the same reason as its three neighbours.
Before and after
Two invisible commas separate three symbols that look like one word.
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
Inside a real subscript index list in MathML.
How to remove it
The default pass removes it. If the subscript structure matters, keep the MathML source and clean only the text you export from it.
Working in a file rather than a paste? The document report for .docx, .odt and .html finds it inside the file, together with hidden runs and tracked changes, without you having to open it. If the question is what the rest of the writing does rather than what this one character does, measure sentence-length variation and see where each habit sits, with no score and no claim about who wrote the text.
Is it an AI watermark?
Used to hide data, but is not a watermark
No. It is one of the four invisible maths operators, used by hidden-payload tools as a convenient alphabet. No model emits it as a mark.
A known carrier for deliberately hidden payloads. Someone put it there on purpose, which is a different question from who wrote the words.
Questions
What is U+2063 used for?
In MathML it separates the indices of a subscript, and that is its only real job. Everywhere else it is simply a convenient invisible character: zero-width steganography uses it as one letter of its alphabet, so searching for u2063 in pasted prose usually turns up a payload rather than a formula.
Why not use a real comma?
Because the rendered formula should show "aij" while the underlying structure still knows there are two indices.
What does it do in plain text?
Nothing visible. It only makes two identical-looking strings compare unequal.
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.
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