• LetterQ[string] yields True if all the characters in the string are letters, and yields False otherwise.
by default gives False
contains any space or punctuation characters.
• LetterQ handles both ordinary and special characters.
treats as letters all special characters explicitly listed as letters in the table in Section A.12.1
• In general, LetterQ treats as letters all characters that appear as ordinary text in any language.
treats as letters such special characters as
does not treat as letters
• New in Version 2; modified in 3.