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G0/G1 character set switching
SI (Shift In, 0x0F) and SO (Shift Out, 0x0E) switch between G0 and G1 character sets. The G0 and G1 sets can be independently designated using
ESC ( X (G0) and ESC ) X (G1), where X selects the character set (B=ASCII, 0=DEC Special Graphics). This mechanism allows applications to quickly toggle between text and line-drawing characters without re-designating the character set each time.How this is testedautomated
Send
Send
\x1b(0 to designate G0 as DEC Special Graphics, write 'l', verify the cell renders as a box-drawing character (not literal 'l'). Restore with \x1b(B.The same probe runs against headless backends (via Termless) and real terminal apps (via a daemon launched in each terminal). This lets us distinguish parser correctness from rendering correctness.
Analysis2026-04-06
Supported by all 12 tested terminals — universal adoption. Part of the Core TUI baseline.
Supported by 13 of 14 backends (93%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✓ yes | |
| VS Code | ✓ yes | ||
| Warp | ✓ yes | ||
| Cursor | ✓ yes | ||
| Terminal.app | ✓ yes |