When to use Underline
Place a line under an expression In source, start from the exact \underline{...} command instead of imitating the rendered glyph with Unicode characters or manual spacing. This keeps the expression editable and gives the renderer enough structure to apply mathematical spacing correctly.
Syntax
\underline{...}The documented syntax belongs to Core LaTeX. Keep every required argument, brace pair, and environment boundary intact when moving the command between an editor, Markdown processor, notebook, or publishing system.
Example
\underline{x}Rendered output
underlined x
Copy and compatibility checks
- Copy
\underline{...}exactly; changing its case or removing a leading backslash can turn it into plain text. - Confirm that the destination loads Core LaTeX before relying on this command.
- Render the example once, then inspect grouping, limits, scripts, and spacing before publishing.