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 ,
Pearson symbol more commonly used hexagonal setting has 3 translation equivalent points per unit cell. The Pearson symbol refers to the hexagonal setting in its letter code ("hR") but the following figure gives the number of translation equivalent points in the primitive rhombohedral setting. Examples: "hR"1 and "hR"2 are used to designate the Hg and Bi structure, respectively. The Pearson symbol should only be used to designate simple structures (elements, some binary compound) where the number of atoms per unit cell equals, ideally, the number of translation equivalent points. Pearson symbol The Pearson symbol, or Pearson notation, is used in crystallography as