Character specified by a three-digit octal code.
Character specified by a one- or two-digit hexadecimal code.
Character specified by any hexadecimal code.
Named control character.
Character contained by given Unicode block or property.
Character not contained by given Unicode block or property.
A single character listed, or contained in a listed range.
A single character not listed, and not contained within a listed range.
POSIX-style character class valid only within a regex character class.
Any character, except newline (unless single-line mode,
One byte; however, this may corrupt a Unicode character stream.
Unicode newline sequence.
Start of string, ...