Topic summary
underline

Extracted from the Wikipedia article Underscore.
As a marker for incorrectness
Underline (typically red or wavy or both) is often used by spell checkers (and grammar checkers) to denote misspelled or otherwise incorrect text.
Topic summary

Extracted from the Wikipedia article Underscore.
Underline (typically red or wavy or both) is often used by spell checkers (and grammar checkers) to denote misspelled or otherwise incorrect text.