(phonetics,dated)A common ad hoc remedy for the lack of type for phonetic symbols on manual typewriters. A letter with the approximate sound would be typed, then the writer would hit backspace and overstrike either with a hyphen (for a narrow letter) or with an underscore after scrolling the paper upward half a line (for a wide letter).
Unicode provides two characters differing only in size, for combining with narrow and wide letters. (The examples above use the short stroke; Latin letters with the long stroke include a̶, b̶c̶d̶e̶g̶h̶n̶m̶o̶p̶u̶ᴜ̶ʊ̶w̶y̶.) However, font support is poor, and Unicode prefers to encode the resulting letters individually, if there is sufficient need, rather than to rely on the diacritics.
Occasionally a letter is seen overstruck with an equals sign ⟨=⟩, as in Ⱡⱡ. This is not supported as a diacritic by Unicode as of 2023.