Unicode Control Characters - Variation Selectors

Variation Selectors

See also: Variation Selectors (Unicode block) and Variation Selectors Supplement

Many characters map to alternate glyphs depending on the context. For example Arabic and Latin cursive characters substitute different glyphs to connect glyphs together depending on whether the character is the initial character in a word, the final character, a medial character or an isolated character. These types of glyph substitution are easily handled by the context of the character with no other authoring input involved. Authors may also use special-purpose characters such as joiners and non-joiners to force an alternate form of glyph where it would not otherwise appear. Ligatures are similar instances where glyphs may be substituted simply by turning ligatures on or off as a rich text attribute.

However, for other glyph substitution, the author's intent may need to be encoded with the text and cannot be determined contextually. This is the case with character/glyphs referred to as gaiji where different glyphs are used for the same character either historically or for ideographs for family names. This is one of the gray areas in distinguishing between a glyph and a character. If a family name differs slightly from the ideograph character it derives from, then is that a simple glyph variant or a character variant. As of Unicode 3.2 and 4.0, the character set now includes 256 variation selectors so that these combining mark characters can select from 256 possible character/glyph variations for the preceding character.