Macron below

Macron below, U+0331◌̱COMBINING MACRON BELOW (HTML ̱), is a combining diacritical mark used in various orthographies.

It is not to be confused with "combining minus below" ̠ (U+0320), "combining low line"   ̲̲ (U+0332) and "low line" ("underscore") _ ). The difference between "macron below" and "low line" is that the latter will result in an unbroken underline when run together, compare a̱ḇc̱ vs. a̲b̲c̲ (of which only the latter should look like abc).