Skip to content

Combining characters (0 cols)

Category: text · Baseline: unicode · Tags: Unicode · Specification ↗

Combining characters (like accents, diacritical marks) attach to the preceding base character and should occupy zero additional columns. For example, é can be written as e + U+0301 (combining acute accent) — the cursor should advance by 1 column, not 2.
How this is testedautomated
Write a base character followed by a combining accent (e.g., e + U+0301), verify the combined character occupies 1 column, not 2.

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 11 of 12 terminals (92%). Not supported by: vt100.js. Part of the Unicode baseline. Notes: vt100.js: Combining characters not implemented — pure TypeScript emulator.

Supported by 13 of 14 backends (93%)

Terminal Applications

TerminalVersionSupportNotes
iTerm23.6.9✓ yes
Ghostty1.3.1✓ yes
VS Code✓ yes
Warp✓ yes
Cursor✓ yes
Terminal.app✓ yes

Headless Backends

Parser correctness only — a means the parser accepts the sequence.

BackendVersionSupportNotes
Alacritty0.26.0✓ yes
Kitty0.40.0✓ yes
vterm0.2.0✓ yes
WezTerm0.1.0-fork.5✓ yes
xterm.js5.5.0✓ yes
vt100.js0.2.1✗ noCombining characters not implemented — pure TypeScript emulator