The basic symbols of keywords and operators in the SQL language are single-byte characters that are part of all IBM character sets. Characters of the language are classified as letters, digits, or special characters.
A letter is any of the 26 uppercase (A through Z) and 26 lowercase (a through z) letters plus the three characters ($, #, and @), which are included for compatibility with host database products (for example, in code page 850, $ is at X'24' # is at X'23', and @ is at X'40'). Letters also include the alphabetics from the extended character sets. Extended character sets contain additional alphabetic characters; for example, those with diacritical (eg., ´) marks. The available characters depend on the code page in use.
A digit is any of the characters 0 through 9.
A special character is any of the characters listed below:
| blank | - | minus sign | |
| " | quotation mark or double-quote | . | period |
| % | percent | / | slash |
| & | ampersand | : | colon |
| ' | apostrophe or single quote | ; | semicolon |
| ( | left parenthesis | < | less than |
| ) | right parenthesis | = | equals |
| * | asterisk | > | greater than |
| + | plus sign | ? | question mark |
| , | comma | _ | underline or underscore |
| | | vertical bar | ^ | caret |
| ! | exclamation mark |
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All multi-byte characters are treated as letters, except for the double-byte blank which is a special character.