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Reverse index (RI)
ESC MRI moves the cursor up one line. If the cursor is at the top margin of the scroll region, the content scrolls down and a blank line is inserted at the top. The sequence is
ESC M. This is the reverse of a line feed at the bottom of the scroll region. Used by applications that need to insert content above the current cursor position.How this is testedautomated
Write 3 lines, move to row 0, send
Write 3 lines, move to row 0, send
\x1bM (RI), verify row 0 is now blank.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 |