Character (character) 
A character (character) is an element of a character string or keyword.
Structure
Syntax
<character> ::= <digit> | <letter> | <extended_letter> | <hex_digit> | <language_specific_character> | <special_character>
End of the code.
Digits
Syntax
<digit> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
End of the code.
Letters
Syntax
<letter> ::= A | B | C | D | E | F | G | H | I | J | K | L | M N | O | P | Q | R | S | T | U | V | W | X | Y | Z a | b | c | d | e | f | g | h | i | j | k | l | m n | o | p | q | r | s | t | u | v | w | x | y | z
End of the code.
Further letters
Syntax
<extended_letter> ::= # | @ | $
End of the code.
Hexadecimal characters
Syntax
<hex_digit> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | a | b | c | d | e | f
End of the code.
Language-Specific Characters
A language-specific character (language_specific_character) is any letter that occurs in a northern, southern, or central European language and is not contained in the list of letters.
Example
German umlauts: ä, ö, ü
French letters with a grave accent: à
End of the example.
If you have installed a UNICODE-enabled database, a language-specific character is a character that is not included in the ASCII code list from 0 to 127.
Special Characters
A special_character is any character that is not contained in the following list:
Digits
Letters
Further letters
Hexadecimal characters
Language-specific characters
Characters that indicate the end of a line in a file