that do not have the expected degree of rounding from the IPA letter they are transcribed with may be clarified as more or less rounded with the over-rounding diacritic and the under-rounding diacritic . These diacritics specify that the vowel lies further toward the rounded or spread end of the roundedness cline.

Thus, has less rounding than cardinal (closer to the open rounding of cardinal or even ), and has greater rounding (closer to that of cardinal ). These diacritics are also used with unrounded vowels: is more spread than