DownArrowUpArrow 
DownArrowUpArrow[x,y,…]
displays as x⇵y⇵….
Details
- DownArrowUpArrow[x,y,…] has no built-in meaning.
- x⇵y is by default interpreted as DownArrowUpArrow[x,y].
- ⇵ can be entered as \[DownArrowUpArrow].
Introduced in 1996
(3.0)
DownArrowUpArrow