Character 
A character is an element of a character string or keyword.
Syntax
<character> ::= <digit>
| <letter>
| <extended_letter>
| <hex_digit>
| <language_specific_character>
| <special_character>
Digits
<digit> ::= 0 | 1 | 2 | | 3 | 4 | 5 | 6 | 7 | 8 | 9
Letters
<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
Further Letters
<extended_letter> ::= # | @ | $
Hexadecimal Characters
<hex_digit> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7
| 8 | 9
| A | B | C | D | E | F
| a | b | c | d | e | f
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.
German umlauts: ä, ö, ü
French letters with a “grave” accent: à
If you have installed a UNICODE-enabled database instance, 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
See also: