A character with the property Grapheme_Extend.

• Grapheme extender characters consist of all nonspacing marks, zero width joiner, zero width non-joiner, U+FF9E, U+FF9F, and a small number of spacing marks.
• A grapheme extender can be conceived of primarily as the kind of nonspacing graphical mark that is applied above or below another spacing character.
• zero width joiner and zero width non-joiner are formally defined to be grapheme extenders so that their presence does not break up a sequence of other grapheme extenders.
• The small number of spacing marks that have the property Grapheme_Extend are all the second parts of a two-part combining mark.
• The set of characters with the Grapheme_Extend property and the set of characters with the Grapheme_Base property are disjoint, by definition.