Close-mid central unrounded vowel Close-mid central unrounded vowel The close-mid central unrounded vowel, or high-mid central unrounded vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is . This is a mirrored letter e, and should not be confused with the schwa , which is a turned e. It was added to the IPA in 1993; before that, this vowel was transcribed (Latin small letter e with umlaut, not Cyrillic small letter yo). Certain older sources transcribe this vowel . The letter may be used with a lowering diacritic ,
Prime (symbol) Prime (symbol) The prime symbol (′), double prime symbol (″), triple prime symbol (‴), quadruple prime symbol (⁗) etc., are used to designate units and for other purposes in mathematics, the sciences, linguistics and music. Although similar in appearance, the prime symbol should not be confused with the apostrophe (’ or '), single quotation mark (' or ‘ or ’), acute accent (´), or grave accent (`); the double prime symbol should not be confused with the double quotation mark (“…” or "…"), the ditto mark (”), or the letter double apostrophe (ˮ). The prime symbol is very similar to