braced-math-scripts (MAT009)

What it does

Warns when a multi-character subscript or superscript is not enclosed in braces. This warning is disabled by default. Enable it with --select MAT009 or add MAT009 to lint.select in the TeXact configuration.

Why is this bad?

In LaTeX, an unbraced script applies only to the next token. For example, x^23 applies 2 as the superscript and leaves 3 on the baseline. Braces make the intended multi-character script explicit.

Example

x^23 + y_ij
x^{23} + y_{ij}