— Variable: char-set:lower-case

All lower-case characters.

— Variable: char-set:upper-case

All upper-case characters.

— Variable: char-set:title-case

This is empty, because ASCII has no titlecase characters.

— Variable: char-set:letter

All letters, e.g. the union of char-set:lower-case and char-set:upper-case.

— Variable: char-set:digit

All digits.

— Variable: char-set:letter+digit

The union of char-set:letter and char-set:digit.

— Variable: char-set:graphic

All characters which would put ink on the paper.

— Variable: char-set:printing

The union of char-set:graphic and char-set:whitespace.

— Variable: char-set:whitespace

All whitespace characters.

— Variable: char-set:blank

All horizontal whitespace characters, that is #\space and #\tab.

— Variable: char-set:iso-control

The ISO control characters with the codes 0–31 and 127.

— Variable: char-set:punctuation

The characters !"#%&'()*,-./:;?@[\\]_{}

— Variable: char-set:symbol

The characters $+<=>^`|~.

— Variable: char-set:hex-digit

The hexadecimal digits 0123456789abcdefABCDEF.

— Variable: char-set:ascii

All ASCII characters.

— Variable: char-set:empty

The empty character set.

— Variable: char-set:full

This character set contains all possible characters.