UpArrowDownArrow 
UpArrowDownArrow[x,y,…]
displays as x⇅y⇅….
Details

- UpArrowDownArrow[x,y,…] has no built-in meaning.
- x⇅y is by default interpreted as UpArrowDownArrow[x,y].
- ⇅ can be entered as \[UpArrowDownArrow].
Examples
See Also
DownArrowUpArrow UpDownArrow DoubleUpDownArrow UpEquilibrium
Tutorials
Introduced in 1996
(3.0)