A combining character with the General Category of Nonspacing Mark (Mn) or Enclosing Mark (Me).

• The position of a nonspacing mark in presentation depends on its base character. It generally does not consume space along the visual baseline in and of itself.
• Such characters may be large enough to affect the placement of their base character relative to preceding and succeeding base characters. For example, a circumflex applied to an "i" may affect spacing ("î"), as might the character U+20DD combining enclosing circle.