x21D6

x21D6, written as Unicode code point U+21D6, is a character in the Arrows block of the Unicode standard. The glyph is generally rendered as a leftward double arrow, though the exact appearance can vary depending on the font and rendering engine. In practice, it is treated as a symbolic arrow and is not tied to a single universal meaning; its interpretation depends on the surrounding notation and the conventions of a given text or field.

Encoding and representation: U+21D6 is encoded in UTF-8 as E2 86 D6 and in UTF-16 as 0x21D6. In plain text and HTML, it can be represented with the numeric character reference as ⇖ or decimal reference as ⇖. Font support for this character is widespread in modern environments, but some rare or stub fonts may substitute a missing glyph with a box or placeholder.

Usage and context: The symbol is used in mathematical, logical, and diagrammatic contexts to denote a leftward directional relation. It may appear in diagrams illustrating mappings, transformations, or relationships that proceed in the leftward direction. It is not a standard operator with a fixed algebraic meaning; instead, it functions as a directional schematic element within expressions, schematics, or formal diagrams.

Related characters: Other nearby arrows include U+21D0 LEFTWARDS DOUBLE ARROW, U+21D4 LEFT RIGHT DOUBLE ARROW, and U+21A4 LEFTWARDS ARROW FROM BAR. These characters share the same general class and are commonly used in similar diagrammatic or mathematical settings.

See also: Unicode Arrows block, related arrow notation in mathematical and logical contexts, font support notes for specialized symbols.