VT Overview

A reference for every escape sequence Otty interprets. Useful if you're writing TUIs, debugging a misbehaving program, or just curious what \x1b[31m actually does.

What "VT" means here

Terminals communicate with the host by exchanging bytes. Most are printable text; some are control sequences that move the cursor, set colors, request information, switch modes, and so on. The vocabulary of these sequences is loosely standardized by ANSI X3.64 / ECMA-48 / ISO 6429 with extensions from DEC VT terminals, xterm, iTerm2, Kitty, and others.

Sequence categories

Category	Introducer	Examples
C0 / Fe	single control byte (0x00–0x1F, 0x7F)	\b BS, \n LF, \r CR, \e ESC
ESC	ESC + one or more bytes (no [)	ESC 7 Save Cursor, ESC # 8 DECALN
CSI	ESC [ … final byte	ESC [ 31 m red, ESC [ H cursor home
OSC	ESC ] … ST	OSC 0 ; <title> set title, OSC 8 hyperlink
DCS / APC / PM	ESC P, ESC _, ESC ^	Kitty graphics, tmux passthrough

How to read these pages

Every sequence page follows the same shape:

1. Sequence — bytes you send, in human-readable notation.
2. Description — what it does.
3. Otty support — implemented, partially implemented, or not supported.
4. Example — a short printf (and otty cli where applicable) demonstrating the effect.

See DECALN for a representative page, or Sequence Reference for the full searchable index.

Sources and conformance

• Otty's terminal core is forked from Alacritty's VT parser.
• Behavior matches DEC VT520 + modern xterm extensions where they disagree.
• Mode reporting (DA1, DA2, DECRQM) advertises the protocols listed in Sequence Reference → "Modes".

Notation conventions

• ESC — 0x1B
• BEL — 0x07
• ST (String Terminator) — either ESC \ (preferred) or BEL (legacy, accepted)
• <n>, <Ps>, <Pt> — numeric / textual parameter placeholders
• ^[, \e, \x1b are all the same ESC byte; this site uses \e.

See also

• Sequence Reference — the full searchable index of every sequence.
• Control Sequences — how the parser routes the four sequence families.
• External Protocols — extensions adopted from other terminals.
• Terminal Comparison — cross-terminal support matrix.