Staircase polyomino

A staircase is a polyomino that is diagonally directed from two opposite corners, creating an ascending or descending staircase shape. These are by definition forks.

Symbol

\textrm{Dir}_{4}^{2\textrm{t}}

Regex

ru(ru)*ld(ld)*

Polyomino list

ru²ld²

ru³ld²

ru³ld³

ru⁴ld³

ru⁴ld²

ru⁴ld⁴