# Special Color Modes (OSC 106)

> The same as OSC 6: turn xterm's special colors on and off.

- **Sequence:** `OSC 106 ; Pc ; Pf ST`
- **ECMA-48:** [§8.3.89 OSC – Operating System Command, p. 51](https://archive.org/details/ecma-48-5th-edition-june-1991/page/n64/mode/1up)
- **xterm:** [Operating System Commands](https://invisible-island.net/xterm/ctlseqs/ctlseqs.html)

`OSC 106 ; Pc ; Pf ST` is the same as [OSC 6](https://control-codes.page/osc/color-mode/index.html.md): it turns
xterm's use of [special color](https://control-codes.page/osc/special-colors/index.html.md) `Pc` on or off. Its
number looks like a reset, as 104, 105 and 110 to 119 are, but it is not
one: xterm sends 6 and 106 to the same code
([`do_osc`](https://github.com/ThomasDickey/xterm-snapshots/blob/xterm-411a/misc.c#L4197-L4248)).

libghostty-vt ignores it, as it does OSC 6, and a case cannot tell that
apart from xterm.

## Validation

### OSC106-1: Nothing on screen, nothing answered

Input, one step per line:

```text
A
\e]106;0;0;1;1\a  # bold off, underline on
B
```

Expected screen:

```text
|AB____|
cursor 1,3
reply none
```

---

This is the Markdown version of <https://control-codes.page/osc/color-mode-106/>. On that page every validation case runs live in libghostty-vt, the terminal emulation core of Ghostty, compiled to WebAssembly.

The validation cases are written in the notation described in <https://control-codes.page/notation/index.html.md>.