chickadee » srfi-14 » char-set:letter

char-set:letterconstant

In Unicode, a letter is any character with one of the letter categories (Lu, Ll, Lt, Lm, Lo) in the Unicode character database.

There are 52 ASCII letters

abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ

There are 117 Latin-1 letters. These are the 115 characters that are members of the Latin-1 char-set:lower-case and char-set:upper-case sets, plus

00AAFEMININE ORDINAL INDICATOR
00BAMASCULINE ORDINAL INDICATOR

(These two letters are considered lower-case by Unicode, but not by SRFI 14.)