Non-printing control character that does not belong in text.
control-charinvisibleThe non-printing control codes inherited from teleprinters and terminals: bell, form feed, escape, delete and their relatives, plus a second block that arrived with the 8-bit character sets.
Tab, line feed and carriage return are excluded. Those do belong in text, and TraceFree never reports them.
From binary data read as if it were text, from a failed encoding conversion, from terminal output pasted into a document, and from files assembled by a program that never expected a human to read them.
In a document, essentially never. Their presence usually means something upstream treated a file as the wrong kind of thing.
| Preset | Action |
|---|---|
conservative | removed |
default | removed |
report-only | asked about |
strict | removed |
Context guards can only ever make a cleanup gentler, never sharper. A rule saying “always remove” does not override them.
In TraceFree, turn on the clipboard watcher and copy the text — the finding appears with a before-and-after comparison of the affected lines. For files, a watched folder does the same, keeping a backup copy alongside.
This page never prints the character itself, only ways of writing it. A page about invisible characters that contained invisible characters would be unreviewable — and that is the problem the program exists to solve.
| Notation | Value |
|---|---|
| Unicode | U+0000 |
| Rust | \u{0} |
| JavaScript, Python | \u0000 |
| HTML | � � |
| Regex (PCRE, Rust) | \x{0} |