CSI scrolling and margins¶

Status: Standard (SU/SD), DEC (margins), xterm (scrollback controls).

Scrolling moves rows within the scrolling region, which defaults to the whole screen. Only text scrolled off the top of the primary screen's region enters scrollback, and only when the region is the full screen in most emulators.

Scroll commands¶

Name	Sequence	Default	Effect
SU	`CSI Ps S`	1	Scroll region up `Ps` rows; blank rows enter at the bottom
SD	`CSI Ps T`	1	Scroll region down `Ps` rows; blank rows enter at the top
IND	`ESC D`		Cursor down; scrolls at the bottom margin
RI	`ESC M`		Cursor up; scrolls at the top margin
NEL	`ESC E`		Like CR LF
LF, VT, FF	`0x0a`, `0x0b`, `0x0c`		Cursor down; scroll at the bottom margin; CR too if LNM (`CSI 20 h`)

CSI Ps T with five parameters is xterm's mouse highlight-tracking initiator (XTHIMOUSE), and CSI > Ps T resets title-mode features. Parsers must dispatch on the parameter count and private marker.

Vertical margins: DECSTBM¶

CSI Pt ; Pb r      set top and bottom margins (1-based, inclusive)
CSI r              reset to the full screen

Setting margins moves the cursor to the home position (respecting origin mode). A region of fewer than two rows is rejected. Applications use DECSTBM to keep a status line fixed while output scrolls above it; DECRQSS with r reads it back.

Horizontal margins: DECSLRM¶

Status: DEC (VT420), opt-in.

CSI ? 69 h         DECLRMM: enable left/right margin mode
CSI Pl ; Pr s      DECSLRM: set left and right margins
CSI ? 69 l         disable; `CSI s` reverts to SCOSC

Support exists in xterm, WezTerm, Ghostty, foot, Contour, and Windows Terminal; VTE, Alacritty, and xterm.js do not implement it (xterm.js documents it as unsupported). Because CSI s changes meaning, applications must check ?69 support with DECRQM before enabling it.

Scrollback¶

Scrollback is outside every standard. Emulator conventions:

Control	Meaning	Status
`CSI 3 J`	Clear scrollback	xterm
`?1049`	Alternate screen, which has no scrollback	xterm
`?1007`	Alternate scroll: wheel sends arrow keys on the alternate screen	xterm
`?1010`	Scroll to bottom on output	xterm
`?1011`	Scroll to bottom on key press	xterm
`CSI ? Ps ; … t`, `Ps` = 14	Reserved by xterm for scrollback size reports; not implemented
`CSI Ps + T`	Unscroll: move `Ps` rows from scrollback back onto the screen, pushing the region down; the inverse of SU into scrollback (kitty 0.20.2+, mintty 3.5.2+); `CSI Ps T` without the intermediate stays SD	Extension

When the scrolling region is smaller than the screen, rows scrolled off its top are discarded, not archived. Terminals differ when the region starts at row 1 but ends above the bottom; xterm archives, several others do not. Applications that want output preserved should leave the region at the full screen.

Reverse wraparound¶

?45 (xterm reverseWrap) lets BS at column 1 move to the end of the previous row. Off by default; used by shells that redraw long prompts.

Probe¶

printf '\033[5;10r'; seq 1 30; printf '\033[r'      # only rows 5-10 scroll
tools/query decrqss r                      # DECRQSS: expect ^[P1$r5;10r^[\ before the reset
tools/query mode 69                        # DECRQM: 1/2 supported, 0 unknown

Sources¶

Compatibility¶

Feature support by terminal. Imported claims have not been reverified; unknown is not unsupported.
Feature / stable ID	Alacritty	Apple Terminal	ConPTY (conhost)	Contour	DomTerm	foot	Ghostty	iTerm2	kitty	Konsole	mintty	mlterm	PuTTY	Revenant	RLogin	st	tmux	rxvt-unicode	VTE	wayst	WezTerm	Windows Terminal	xterm	xterm.js
SU/SD `csi-su-sd-scroll`	SupportedImported · unverified	SupportedImported · unverified	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	Unknown	Unknown	SupportedImported · unverified	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified
DECSTBM `csi-decstbm`	SupportedImported · unverified	SupportedImported · unverified	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	Unknown	Unknown	SupportedImported · unverified	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified
DECSLRM / ?69 `csi-decslrm`	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	UnsupportedImported · unverified
1007 alternate scroll `dec-mode-1007-alternate-scroll`	SupportedImported · unverified	Unknown	Unknown	Unknown	Unknown	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified	SupportedImported · unverified
?45 reverse wrap `dec-mode-45-reverse-wrap`	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown	Unknown	SupportedImported · unverified	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	SupportedImported · unverified	Unknown	SupportedImported · unverified	SupportedImported · unverified
SL shift left `csi-sl`	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown
SR shift right `csi-sr`	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown
SU scroll up `csi-su`	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown
SD scroll down `csi-sd`	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown
Unscroll (CSI + T) `csi-plus-t-unscroll`	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Supported	Unknown	Supported	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown	Unknown