DoubleStruckA ... DoubleStruckZ
... \[DoubleStruckA] ... \[DoubleStruckZ]
Aliases: dsa through dsz.
Treated as distinct characters rather than style modifications of ordinary letters.
Contiguous character codes from the private Unicode character range are used, even though a few double-struck characters are included in ordinary Unicode.
See The Mathematica Book: Section 3.10.3.
See also: \[DoubleStruckCapitalA] , \[GothicA] , \[ScriptA] , etc.