DECSLRM

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Standard

DECSLRM (Set Left and Right Margins) is a CSI sequence that defines horizontal scrolling margins. It is only active when left/right margin mode (DECLRMM, mode 69) is enabled.

Syntax

CSI Pl ; Pr s     DECSLRM — Set Left and Right Margins

Formal syntax

DECSLRM = 0x1b, "[", [ Pl, [ ";", Pr ] ], "s" ;
Pl = digit, { digit } ;                 (* left margin, default: 1 *)
Pr = digit, { digit } ;                 (* right margin, default: screen width *)
digit = "0" | "1" | "2" | "3" | "4"
    | "5" | "6" | "7" | "8" | "9" ;

Parameters

Parameter	Description	Default
Pl	Left margin column	1
Pr	Right margin column	Screen width

Description

Per the VT510 manual, DECSLRM sets the left and right margins of the scrolling region. Pl must be less than Pr. The sequence is only recognized when DECLRMM (mode 69) has been enabled via CSI ? 69 h.

When left/right margins are active, the following operations are confined horizontally:

• Character insertion and deletion (ICH, DCH)
• Erase operations respect the margins
• Cursor wrapping at end of line wraps within the margin area
• Scrolling operations are confined to the rectangular region defined by both vertical (DECSTBM) and horizontal (DECSLRM) margins

CSI s with no parameters resets the left and right margins to the full screen width.

Conflict with SCP

CSI s is also used for SCP (Save Cursor Position). When DECLRMM (mode 69) is enabled, CSI s with parameters is interpreted as DECSLRM. Applications that need both left/right margins and cursor save should use DECSC/DECRC (ESC 7 / ESC 8) instead of SCP/RCP.

Examples

printf '\e[?69h'         # Enable left/right margin mode
printf '\e[5;40s'        # Set left margin to 5, right margin to 40
printf '\e[?69l'         # Disable left/right margin mode

Specifications

Specification	Section
VT510 Reference	—

Terminal support

Terminal	Support	Version	Notes
Terminal Emulators
Alacritty	✗	No	No evidence of left/right margin support
Bobcat	✓	0.9.0	Supported via TerminalCtrl library
contour	✓	v0.1.0	Requires DECMode::LeftRightMargin to be enabled
foot	✗	No	Not implemented; CSI s is used for save cursor instead
Ghostty	✓	v1.0.0	Requires mode 69 to be enabled
iTerm2	✓	Yes	VT100CSI_DECSLRM token parsed and executed via terminalSetLeftMargin:rightMargin:, requires Mode 69 enabled
Kitty	✗	No	DECSLRM (CSI s) not supported. CSI s only handles save cursor (ANSI.SYS) and save modes
Konsole	✗	No	No left/right margin support found; only top/bottom margins implemented
mintty	✓	Yes	DECSLRM (CSI s) at line 3391-3400, requires Mode 69 (lrmargmode)
mlterm	✓	rel-2_9_0	Implemented at vt_parser.c:5879-5890; Requires Mode 69 (DECLRMM) to be enabled
PuTTY	✗	No
Rio	✗	No	Left/right margins not implemented
rxvt-unicode	✗	No	Left/right margins not implemented
st	✗	No	CSI ? r goes to unknown handler; left/right margins not implemented
terminology	✓	v1.1.0	Requires Mode 69 (lr_margins)
VT100	✗	No
VTE	✓	Yes	Requires Mode 69 (DECLRMM) to be set, conflicts with SCOSC on CSI s
WezTerm	✓	Yes	DECSLRM implemented as Cursor::SetLeftAndRightMargins. Requires Mode 69 (DECLRMM) to be set. CSI s is ambiguous with save cursor
Windows Terminal	✓	Yes	Requires Mode 69 (DECLRMM). Implemented in ITermDispatch.hpp:75 as SetLeftRightScrollingMargins. CSI s is interpreted as DECSLRM when DECLRMM is enabled, otherwise as ANSISYSSC.
xterm	✓	xterm-406	Requires DECLRMM mode enabled
xterm.js	✗	No	Not implemented; CSI s is used for ANSI save cursor instead
Multiplexers
cy	✗	No
GNU Screen	✗	No	Left/right margins not implemented
tmux	✗	No	Not implemented for input; CSI s maps to SCP instead; margins feature used only for output
tuios	✓	v0.0.15	Requires Mode 69 (ModeLeftRightMargin) to be set
Zellij	✗	No

See also

• DECSTBM — Set Top and Bottom Margins — Vertical scrolling margins
• SCP/RCP — Save/Restore Cursor — Shares the CSI s sequence