South East Double Arrow

South East Double Arrow at U+21D8 is a diagonal arrow symbol pointing down and to the right with a double-stroked shaft, used to show a strong or formal direction toward the southeast. It is part of the Arrows block, where it sits among other single and double directional arrows for diagrams, notation, and technical text. Its main use is in mathematical and logical writing, especially where double arrows suggest implication, correspondence, transformation, or a directed relation rather than simple movement. In a commutative diagram, process sketch, or proof note, A ⇘ B can indicate a mapping or consequence that runs diagonally downward to the right. It also appears in user interfaces, documentation, and layout diagrams when a designer needs a compact southeast direction marker with more emphasis than a plain arrow. For example, it may label a diagonal navigation path, a branch in a flowchart, or a movement on a grid from an upper-left cell toward a lower-right cell. The symbol is less common in everyday prose than standard rightward or downward arrows, and it can be confused in meaning with the single-stroke southeast arrow when the double line is not semantically important. Its usefulness depends on the surrounding notation: the double stroke usually signals a deliberate relation, not merely a decorative arrow.