Primary device attributes (DA1)

Category: device · Tags: ECMA-48 Standard, VT100 · Specification ↗

DA1 (Primary Device Attributes) lets applications identify the terminal type and its capabilities. The query is ESC [ c or ESC [ 0 c. The terminal responds with ESC [ ? attributes c where attributes is a semicolon-separated list of capability codes. DA1 is one of the first sequences an application sends to discover what the terminal supports. The response identifies the terminal class (VT100, VT220, etc.) and optional capabilities. Modern terminals typically identify as VT220 or higher with various capability flags. Shell integration scripts and TUI frameworks use DA1 to enable or disable features based on terminal capabilities.

Supported by 0 of 6 backends (0%)

Support Matrix

Backend	Version	Support	Notes
Alacritty	0.26.0	~ partial	Headless mode has no output stream for DA1 responses
Ghostty	1.3.1	~ partial	Headless mode has no output stream for DA1 responses
Kitty	0.40.0	~ partial	Headless mode has no output stream for DA1 responses
WezTerm	0.1.0-fork.5	~ partial	Headless mode has no output stream for DA1 responses
xterm.js	5.5.0	~ partial	Headless mode has no output stream for DA1 responses
vt100	0.1.0	✗ no	No output stream — pure TypeScript emulator

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