All Unicode characters are accepted.

<Literal>      ::=  <StringLiteral> | <NumericLiteral>

String literals must be surrounded by single-quotes. Embedded single-quotes and backslashes must be escaped by backslashes. Numeric literals can be integers or floating point numbers. However, they do not support exponential notation, and they cannot have trailing f|F|d|D to indicate float or double.

Some example literals:

34   .34   'jim'   'àlêx\'s house'

Identifiers can either be quoted (using double-quote characters) or unquoted.

<Key>          ::=  <Identifier>

Unquoted identifiers can contain only letters, digits, and underscores, and cannot start with a digit. Quoted identifiers can contain any character, but double-quotes and backslashes must be escaped using a backslash.

To make some text be interpreted as an identifier instead of as a keyword, simply place it within quotation marks. For example if you have a property named WHERE or GROUP, you can reference it as "WHERE" or "GROUP". (Omitting the quotation marks would lead to a syntax error.)

Some example identifiers:

àlêx4
"4th street"
"some ,*#\" funny \\;% characters"