Unicode: FE38. Alias: Esc u{ Esc. Letter-like form. Extensible character.
Unicode: 23B5. Alias: Esc u[ Esc. Letter-like form. Extensible character.
Unicode: FE36. Alias: Esc u( Esc. Letter-like form. Extensible character.
Unicode: 21C5. Infix arrow operator. x ⇅ y is by default interpreted as UpArrowDownArrow[x,y]. Extensible character.
Unicode: 2195. Infix arrow operator. x ↕ y is by default interpreted as UpDownArrow[x,y]. Extensible character.
Unicode: 296E. Infix arrow-like operator. x ⥮ y is by default interpreted as UpEquilibrium[x,y]. Extensible character.
Unicode: 03C5. Aliases: Esc u Esc, Esc upsilon Esc. Greek letter.
Unicode: 21A5. Infix arrow operator. x ↥ y is by default interpreted as UpTeeArrow[x,y]. Extensible character.
\[Xi]
(Mathematica Character Name) Unicode: 03BE. Aliases: Esc x Esc, Esc xi Esc. Greek letter.
\[Xor]
(Mathematica Character Name) Unicode: 22BB. Alias: Esc xor Esc. Infix operator with built-in evaluation rules. x ⊻ y is by default interpreted as Xor[x,y].