# Cursor Keys Mode (DECCKM)
> Choose what the arrow keys send: cursor movement or application codes.
- **Sequence:** `CSI ? 1 h`
- **DEC STD 070:** [§6.8 Set/Reset Cursor Key Mode, p. 6-62](https://archive.org/details/bitsavers_decstandar0VideoSystemsReferenceManualDec91_74264381/page/n548/mode/1up)
- **VT220:** [§4.6.8 Cursor Key Mode (DECCKM)](https://vt100.net/docs/vt220-rm/chapter4.html#S4.6.8)
- **VT510:** [DECCKM—Cursor Keys Mode](https://vt100.net/docs/vt510-rm/DECCKM.html)
`CSI ? 1 h` sets cursor keys mode to *application* and `CSI ? 1 l` resets
it to *cursor*, the default. It changes what the four arrow keys send to the
host. Reset, they send ANSI cursor movement sequences, `ESC [ A` for up.
Set, they send application codes introduced by SS3 instead, `ESC O A` for up,
similar to what the numeric keypad sends in application mode. DEC STD 070
tabulates both sets of codes in
[§6.8.2, p. 6-61](https://archive.org/details/bitsavers_decstandar0VideoSystemsReferenceManualDec91_74264381/page/n547/mode/1up).
DEC STD 070 requires, from level 2, that this mode and the keypad mode
([DECKPAM](https://control-codes.page/esc/deckpam/index.html.md)) be independent of each other.
This site cannot press keys, so the cases check only the mode, through
DECRQM, and that nothing on the screen changes.
## Validation
### DECCKM-1: Set
Input, one step per line:
```text
\e[?1h
AB
\e[?1$p # DECRQM: is mode 1 set?
```
Expected screen:
```text
|AB___|
reply \e[?1;1$y
```
### DECCKM-2: Reset
Input, one step per line:
```text
\e[?1h
\e[?1l
\e[?1$p
```
Expected screen:
```text
|_____|
reply \e[?1;2$y
```
### DECCKM-3: Cursor mode to begin with
Input, one step per line:
```text
\e[?1$p
```
Expected screen:
```text
|_____|
reply \e[?1;2$y
```
---
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 .