A character with the General Category of Combining Mark (M).

• Combining characters consist of all characters with the General Category values of Spacing Combining Mark (Mc), Nonspacing Mark (Mn), and Enclosing Mark (Me).
• All characters with non-zero canonical combining class are combining characters, but the reverse is not the case: there are combining characters with a zero canonical combining class.
• The interpretation of private-use characters (Co) as combining characters or not is determined by the implementation.
• These characters are not normally used in isolation unless they are being described. They include such characters as accents, diacritics, Hebrew points, Arabic vowel signs, and Indic matras.
• The graphic positioning of a combining character depends on the last preceding base character, unless they are separated by a character that is neither a combining character nor either zero width joiner or zero width nonjoiner. The combining character is said to apply to that base character.
• There may be no such base character, such as when a combining character is at the start of text or follows a control or format character—for example, a carriage return, tab, or right-left mark. In such cases, the combining characters are called isolated combining characters.
• With isolated combining characters or when a process is unable to perform graphical combination, a process may present a combining character without graphical combination; that is, it may present it as if it were a base character.
• The representative images of combining characters are depicted with a dotted circle in the code charts. When presented in graphical combination with a preceding base character, that base character is intended to appear in the position occupied by the dotted circle.