# Cursor Down (CUD)
> Move the cursor down n lines.
- **Sequence:** `CSI Pn B`
- **Defaults:** Pn = 1
- **ECMA-48:** [§8.3.19 CUD – Cursor Down, p. 36](https://archive.org/details/ecma-48-5th-edition-june-1991/page/n49/mode/1up)
- **DEC STD 070:** [§5.4.4 Cursor Down, p. 5-43](https://archive.org/details/bitsavers_decstandar0VideoSystemsReferenceManualDec91_74264381/page/n297/mode/1up)
- **VT220:** [§4.7 Cursor Positioning](https://vt100.net/docs/vt220-rm/chapter4.html#S4.7)
- **VT510:** [CUD—Cursor Down](https://vt100.net/docs/vt510-rm/CUD.html)
Move the cursor `Pn` lines down, keeping its column. A `0` is taken as `1`.
The cursor stops at the bottom margin if it started at or above it. A cursor
already below the bottom margin stops at the last line instead. CUD never
scrolls, which is the difference between it and a [line feed](https://control-codes.page/c0/lf/index.html.md): at
the bottom margin a line feed scrolls the region up, and CUD stays put.
Moving the cursor cancels any pending wrap. DEC STD 070 calls the pending
wrap the *Last Column Flag*, and its appendix on autowrap lists this among
the controls that should reset it
([§D.6.1, p. D-13](https://archive.org/details/bitsavers_decstandar0VideoSystemsReferenceManualDec91_74264381/page/n1199/mode/1up)); xterm clears it in
[`CursorDown`](https://github.com/ThomasDickey/xterm-snapshots/blob/xterm-411a/cursor.c#L251-L263), and libghostty-vt does the same.
[CUU](https://control-codes.page/csi/cuu/index.html.md) goes the other way, and [CNL](https://control-codes.page/csi/cnl/index.html.md) moves down and
returns to the left margin as well.
## Support
| Terminal | Version | Support | Notes |
| --- | --- | --- | --- |
| VT220 | [manual](https://vt100.net/docs/vt220-rm/), 2nd ed., 1984 | Yes | [§4.7 Cursor Positioning](https://vt100.net/docs/vt220-rm/chapter4.html#S4.7) |
| VT510 | [manual](https://vt100.net/docs/vt510-rm/), 1st ed., 1993 | Yes | [CUD](https://vt100.net/docs/vt510-rm/CUD.html) |
| xterm | patch 412, [xterm-411a](https://github.com/ThomasDickey/xterm-snapshots/tree/xterm-411a) | Yes | |
| libghostty-vt | [0f171f6](https://github.com/ghostty-org/ghostty/tree/0f171f650a1cbbd6df4a2573b6b0c7de57cc6d90) | Yes | |
| kitty | 0.49.1, [run in a VM](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/kitty.json) | Yes | passes the 5 cases that show it working |
| foot | 1.28.0, [run in a VM](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/foot.json) | Partly | fails CUD-3 of the 5 cases that show it working |
| pyte | 0.8.2, [run as a library](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/pyte.json) | Partly | fails CUD-4, CUD-5 of the 5 cases that show it working |
| xterm.js headless | 6.0.0, [run as a library](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/xtermjs.json) | Yes | passes the 5 cases that show it working |
| alacritty_terminal | 0.26.0, [run as a library](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/alacritty.json) | Partly | fails CUD-3 of the 5 cases that show it working |
| ConEmu | build 230724, its [documentation](https://conemu.github.io/en/AnsiEscapeCodes.html) | Yes | lists `ESC [ lines B`: [ANSI escape codes](https://conemu.github.io/en/AnsiEscapeCodes.html) |
| rxvt-unicode | 9.31, [run in a VM](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/urxvt.json) | Yes | passes the 5 cases that show it working |
| VTE | 0.84.1, [run as a library](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/vte.json) | Yes | passes the 5 cases that show it working |
## Validation
### CUD-1: Down one line
Input, one step per line:
```text
\e[1;2H
\e[B
X
```
Expected screen:
```text
|_____|
|_X___|
|_____|
```
### CUD-2: Down n lines, stopping at the last line
Input, one step per line:
```text
\e[1;2H
\e[9B
X
```
Expected screen:
```text
|_____|
|_____|
|_X___|
```
### CUD-3: Stops at the bottom margin, without scrolling
Input, one step per line:
```text
A
\e[1;3r # region is lines 1 to 3
\e[2;1H
\e[9B
X
```
Expected screen:
```text
|A____|
|_____|
|X____|
|_____|
```
### CUD-4: Below the bottom margin
Input, one step per line:
```text
\e[1;2r # region is lines 1 and 2
\e[3;1H # below it
\e[9B
X
```
Expected screen:
```text
|_____|
|_____|
|_____|
|X____|
```
### CUD-5: From a pending wrap
Input, one step per line:
```text
ABCDE # fills the line; a wrap is pending
\e[B
X
```
Expected screen:
```text
|ABCDE|
|____X|
|_____|
```
---
This is the Markdown version of . 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 .