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Tertiary Device Attributes (DA3)
ESC [ = cDA3 (CSI = c) returns the terminal's unit ID as a DCS response. Less commonly supported than DA1/DA2, primarily by xterm and terminals that aim for high VT compatibility.
Analysis2026-03-26
Supported by 1 of 8 terminals (13%). Part of the Rich TUI baseline. Notes: Kitty: Headless mode has no output stream for DA3 responses.
Supported by 2 of 13 backends (15%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✗ no | No DA3 response |
| VS Code | 1.112.0 | ✗ no | No DA3 response |
| Warp | 0.2026.03.18.08.24.03 | ✗ no | No DA3 response |
| Cursor | 2.6.21 | ✗ no | No DA3 response |
| tmux | 3.6a | ✗ no | tmux intercepts DA3 and does not forward it to the outer terminal |
| Kitty | 0.46.2 | ✗ no | Headless mode has no output stream for DA3 responses |
| Terminal.app | 2.15 | ✗ no | No DA3 response |
| GNU Screen | 5.0.1 | ✗ no | Screen does not forward DA3 to the outer terminal |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| vterm | 0.2.0 | ✓ yes | |
| Alacritty | 0.26.0 | ~ partial | Headless mode has no output stream for DA3 responses |
| WezTerm | 0.1.0-fork.5 | ~ partial | Headless mode has no output stream for DA3 responses |
| vt100 | 0.2.1 | ✗ no | No output stream — pure TypeScript emulator |