Unicode: 2222. Letter-like form. Used in geometry to indicate a spherical angle, as in the symbol ∢ ABC.
Unicode: 2294. Infix operator. x ⊔ y is by default interpreted as SquareUnion[x,y]. Used in mathematics to denote various forms of generalized union, typically of disjoint ...
Unicode: 2245. Alias: Esc ~== Esc. Infix similarity operator. x ≅ y is by default interpreted as TildeFullEqual[x,y]. Used in mathematics to indicate isomorphism, congruence ...
Unicode: 228E. Infix operator. x ⊎ y is by default interpreted as UnionPlus[x,y]. Used to denote union of multisets, in which multiplicities of elements are added.
Unicode: 2196. Infix arrow operator. x ↖ y is by default interpreted as UpperLeftArrow[x,y]. Extensible character; grows by default to limited size.
Unicode: 2197. Infix arrow operator. x ↗ y is by default interpreted as UpperRightArrow[x,y]. Extensible character; grows by default to limited size.
Unicode: 22EE. Letter-like form. Used to indicate omitted elements in columns of a matrix.
Unicode: F725. Letter-like form. Used in yellow to indicate messages and other warnings in the default style for Mathematica notebooks. Based on an international standard ...
Unicode: 231A. Letter-like form. Used to indicate a calculation that may take a long time.
$DefaultImagingDevice gives the name of the default imaging device attached to the computer.