POSIX-compatible classes

These take the form of "\p{Keyword}" and "\P{Keyword}" for normal and negated variants.

Code Description Represents Notes
Alpha any letter [a-zA-Z]
Upper uppercase letters [A-Z]
Lower lowercase letters [a-z]
Digit decimal digit [0-9]
Alnum alphanumeric [a-zA-Z0-9] this is not the same as \w since it excludes "_"
XDigit hexadecimal digit [a-fA-F0-9]
Punct punctuation [!"#$%&'()*+,-./:;<=>?@\[\\\]\^_`|{}~]
Graph graphic character [\p{Alnum}\p{Punct}]
Print printable character [\x20-\x7E] Graph and space (excludes newlines and tab).
Blank tab or space [ \t]
Space any whitespace \s
Cntrl any control character [\x00-\x1F\x7F]

These keywords are case-sensitive - i.e. "\p{alpha}" will cause an error.

Note also that the "[:alpha:]" syntax used by other regex implementations does not work.